Filing is done by the applicant, who is generally the employer of the inventor (i.e. the company they work for). Each inventor must have made a significant innovative technical contribution to the invention, and anyone who makes such a contribution has to be an inventor. Managing or employing an inventor doesn't count. The only bias I can think of is that the patent might be filed some time after the invention was made, but in my experience this is at most a few years, usually one or two. Source: I am an inventor on six patents (average age 40).

Or to private people who have money.

Guess what most twenty year old don't have?

I'd be very surprised if more than an handful of cases fall into that category. Do you have any data showing that is significant?

Vox had an article on something related to this [0], but you'd have to take an extra step to say this means these the inventors, at 20-years-old, were or weren't obtaining patents because of parent income.

[0] https://www.vox.com/2015/3/16/8225165/patents-innovation-soc...