I don't think the renting example is that true. AFAIK auto manufacturers certainly do "rent" many of the factory machinery they use, and they certainly "rent" the maintenance contracts from the companies who service them (the big exception I'm aware of being Toyota, which makes their own factory robotics).
In other examples, many airlines do lease airplanes, and even among the airlines that do own the planes, they still usually lease the engines.
As the GP said, there's a balance to be struck. Delta doesn't have the expertise or the economies of scale necessary to build their own engines from scratch, but they do have the ability to lease those engines and then have their own teams maintain them. Similarly, most companies don't have the know-how or the EoS to run their own data center, so instead they buy cloud services and then have a smaller team to maintain it. It's a win-win. Some companies like BofA might be big enough where they can run their own cloud and it be cheaper than using a cloud provider, but that's definitely not a common thing.
Could you clarify "AFAIK auto manufacturers certainly do "rent" many of the factory machinery they use, and they certainly "rent" the maintenance contracts from the companies who service them (the big exception I'm aware of being Toyota, which makes their own factory robotics)."?
Rental only makes sense if there is a marketplace for used machines. Eg, planes and plane engines are components that aren't really tied to one place or company. (The "that aren't easily replaceable" from the parent post.)
But industrial robots for car manufacturing seems like rather specific hardware. If, say, the Ford plant in Claycomo, Missouri no longer needs a machine for making the F-150, who is going to rent it? How is rental a better cost-savings for Ford than buying the machine and later selling it?
Also, '"rent" the maintenance contracts' doesn't make sense to me. I sell maintenance contracts to my customers, I don't rent them, and I don't understand what "rent" could even mean in that context.
The difference between renting and purchasing gets murky (sure, not literally) when you are dealing with sensitive hardware that you rely on but cannot maintain yourself. Such systems usually require frequent maintenance by the supplier. Sure, you could end your maintenance contracts, but then the systems you have purchased will very rapidly become useless. The up-front cost of hardware is often very small compared to the ongoing cost of maintenance contracts, and so the relationship ends up looking a lot like rental.
The parent comment mentions that Delta rents their airplane engines. I imagine that they have the capability to do general maintenance on the engines, but that the engines need to be periodically sent back to the supplier (probably GE or Rolls-Royce) for a teardown, safety inspection, and rebuild. Without regular inspections an engine can't be flown, and is essentially worthless. Not much point in actually owning the engine if you can't use it.
I guess I have a naive view. I think of "buy" as something which is a capital expenditure, can be depreciated, etc. while "rent" are things which fall under operational expenditure.
With that in mind, I can see support contracts as an operational expenditure.
But if "over half of industrial robot purchases in North America have been made by automakers" then that's a lot of capital expenditure. I never got the feel that the companies which make modern industrial robots primarily rented them out (akin to IBM's renting out of tabulation machines 100 years ago). I really thought they mostly sold the robots.
Many of these industrial systems are built from reusable components. In my experience at a Tier 1 OEM for the US domestic auto market, a line could be torn down and re-purposed to another line by adding or removing physical components, modifying the physical layout where appropriate, and then adjusting the PLC programming.
An assembly line isn't really a "product," per se. It's more of amalgamation of several products and technologies, many legacy, that forms a cohesive but loosely-coupled whole. You may have several vendors' products / systems in a line. So what you end up with are ongoing contracts that provide for installation, programming, troubleshooting, maintenance, etc.
There's actually a whole specialized industry that does nothing but design assembly lines. It's pretty neat.
They probably do sell them. I believe most industrial robotics systems are built custom, or at least heavily customized. But I have no idea (and I'm sure they closely guard) what percentage of their revenue comes from direct sales and what comes from support contracts. Somewhat related, I recall reading that one of the things that caused financial issues for GE Power was broken incentives around support contracts. To meet quarterly targets the sales team started offering to trade larger up-front prices for reduced costs on support contracts so as to frontload revenue. Too many customers saw the golden opportunity and GE ended up losing a ton of money.
It's more common than you think. In industries that are locked into legacy apps, cloud costs are massive. Same for industries where storing massive amounts of data for decades is normal. Healthcare and banking spring to mind. I wouldnt be surprised if big pharma are private cloud too.
There are quite many different types of airlines. If you show up for some flight, it might actually be operated by personnel that are on the books of some other airline.
There's Boeing which also used to have an airline. It was made illegal IIRC.
And there are things in between these two extremes.
Some airlines have a heavy maintenance organization. Some have outsourced it. Different companies have different market segments and safety records etc.
In other examples, many airlines do lease airplanes, and even among the airlines that do own the planes, they still usually lease the engines.
As the GP said, there's a balance to be struck. Delta doesn't have the expertise or the economies of scale necessary to build their own engines from scratch, but they do have the ability to lease those engines and then have their own teams maintain them. Similarly, most companies don't have the know-how or the EoS to run their own data center, so instead they buy cloud services and then have a smaller team to maintain it. It's a win-win. Some companies like BofA might be big enough where they can run their own cloud and it be cheaper than using a cloud provider, but that's definitely not a common thing.