Vending machines are not passive! They need repair, management of the money, if they sell goods then they need restocking (and that restock needs to be purchased), and you have to negotiate for location location location.
And if coins are involved there is work to collect the coins and get them to the bank.
Lastly, running a vending machines company requires regular involvement to make sure everything is running.
This is still passive. This is similar to owning 10 apartment buildings. You have to hire managers to deal with all the day-to-day, but there is still money left over. You just have to make sure that they aren't stealing from you. Similar to a lot of investments, which I would also consider passive income. Even with stocks, you can't just sleep or you could end up in a bad way, but you are also not putting in 8 to 12 (or more sometimes) hours of work a day like a small business.
Clearly it's a spectrum with one side being low intensity/low return, and the other being high intensity/high return. The only question is to ask yourself where you want to be on that spectrum.
Same can be said of any type of 'passive' income. In general, I take passive to imply you get out more than you put in. It's the ratio of time invested to time physically working.
And if coins are involved there is work to collect the coins and get them to the bank.
Lastly, running a vending machines company requires regular involvement to make sure everything is running.