Compatibility or bug fixes aren't free for all users because just like features, the developer had to spend time building them and needs to get paid for that time.
I build a house for you for $X. You find out that the lights don't work and ask me to fix it. Would you be happy if I told you "Oh, sorry I messed up the electrical connections. It'll cost you $Y though, because I have to spend time fixing them and I need to get paid for that time."?
You build a house for me for $X. Two years later, I notice that if you hang three towels on the bathroom door on a humid day while the living room light was on, the door didn't close properly. Would you be happy if I came to you and demanded that you debug and fix this problem for free? Didn't I pay for a working house the first time?
I very much do not believe that you paid me enough for me to guarantee that my product would work in all circumstances forever. If you did, then by golly I'm yours for life buddy!
If the problem is due to my poor worksmanship and it has always been there since the very beginning (even though you may not have noticed it for 2 years), I'd gladly fix it for free. Of course, with a bathroom door you'd have to prove it's not due to wear and tear, but this doesn't apply to software - the bits in your binary don't change with time.
In perpetuity? When a major OS upgrade breaks the app completely after being in use with no problems for 5 years?
Again we find that conflating real-world examples with technology issues is a bad way of understanding them. With a house you typically have a warranty period and afterwards are required to pay for fixes yourself.
There is a lot of grey here that paid updates help deal with. The users will vote with their wallets if they feel they're being thoroughly fleeced.
But why should the users be responsible for compensating the developer when it is Apple who changed something in the OS? Perhaps the developers should ask Apple to pay for their time.
The way I see software (excluding SAAS and software that comes with an explicit service contract) is the moment you pay your money, and the software is "fit for the purpose" that you were sold it for, you might be stuck with that version forever.
If there is a massive OS upgrade on the horizon that might break it - don't spend the money on it. Don't expect anyone to pay for it but the end user.
Expecting developers to support the product until the heat death of the universe without ongoing compensation is ridiculous.
Now of course there are variations on this that developers can be nice and provide if they feel like it, but I never expect anything I buy to have any more support than was explicitly outlined to me when I laid down the money.
