There's somewhere in the ballpark of 166,000 employees at Apple, just unfathomable scale [1]. It is not unreasonable to ask that someone specific is responsible for each particular small feature and ensuring it keeps working. Trying to apply an economic analysis to such a "free as in beer" operating system does not seem to work well. Consider the question of "how many small holes can you have in your wooden sailing ship"?
Not that it impacts your argument significantly, but for the sake of completeness, Apple employs a huge number of retail employees.
Yes. A more useful number would be how many employees are working on macOS specifically. Hard to find a definitive number for that.
Less than 1% of that number. Of course this is hard to actually count properly since there is a lot of shared work across platforms.
It’s not unreasonable to ask but they can and are saying “no”.