alt Hacker NewsYour response suggests that you're only considering native apps where users can view memory usage.
For cloud apps where the costs are largely hidden from users, the user has no way of doing that analysis. I agree with the second part of what you said, though: I expect businesses to just raise their prices in those cases rather than systematically focus on actual difficult engineering problems.
For cloud apps incentives are aligned already. The cost of memory usage falls on the people who are both paying for it and can control it. It's only really on end user devices where it's a problem, and only really on desktop class machines. iOS and Android were built in a RAM starved environment anyway and aggressively kill any non-foreground process that is using too much memory.