Going to have to disagree with the 1st part. It's not that difficult to get a Money Transmitter License in some locations. Expensive perhaps depending on if you are actually making any money. Time consuming definitely in some areas. But even in NYS it not hard. It's just forms you have to fill out and records you have to keep. AND if you are actually making money running it as a business these are records you would have to keep anyway.
The bold is the part I was trying to get at because most open-source projects don't make a ton of money, even with donations.
True, but there are a bunch that make their money elsewhere like taking a % of an exchange service that the wallet offers, or placing ads, things like that.
Add on other services that they may or may not offer (buying - selling) and I can see them making some money.
AND if it's part of another project then you don't know what else they are doing for cash flow.
Probably not that important as to the why, as said and what should be in just about any post in this topic as a reminder.
Just don't just custodial wallets.
-DAve