What do you mean “cost them money” I legitimately can’t think of situation where releasing a product behind deadline would cost a business money? Obviously they just allocated resources more efficiently because they have fewer people. Likely they made more money because of increased demand.
Different businesses have different meanings to deadlines and timelines.
If it's v6.8 of your internal software product, no, the deadline doesn't usually matter that much. Maybe you are a bit behind your competition, but the only problem with just being at the 6.7 feature set a little longer is a small percentage of customers not sticking around. Your manager probably overpromised and underestimated, but aside from a bit of abuse and panic, you're right, it doesn't really matter.
But if you're one of 120 companies building parts for the 2025 F150 and your part isn't ready and the other 119 companies are ready, whether it's your supplier or you or your customer who is behind, you'd better believe that they've got you over a barrel in the contract. Like, the contract has a line that reads "for every minute of downtime after [date] you owe $25k". Your PM hopefully underpromised with an aim to overdeliver, but missed really bad. And all the checks and balances failed. If you've got adequate financials you can survive a miss once in a great while, but two or three in a row and even big shops will go under.
It's often important to understand the consequences of missed deadlines that your coworkers, vendors, or especially customers are accustomed to, people have wildly disparate experiences in this area.
I have a product that can bring in $10,000 in profit each week. If I launch it four weeks late, I just lost $40,000.
Or I have a product that relies on certain hardware. I've already bought/leased that hardware, so I'm now paying depreciation/lease payments for that hardware. Every week I delay the launch I'm losing money on those payments because the hardware is sitting unused.
It is fairly obvious. If it is expected that a product or set of features will drive X revenue per month, and you are late by Y months, then a decision that directly contributes to that delay just cost the company money.
In addition to everything mentioned here, projects based on holiday dates (Christmas sale feature, Thanksgiving promotions etc) not rolling out on time means that the feature can go out only in the next year.
Some contracts specify liquidated damages if deadlines are not met. The contracts I’ve been a party to have daily cash penalties that will quickly erode any margin away.
