The payment technology is less of an issue. Consumers been able to send small amounts of money all over the world for a decade or two. It’s more about the regulatory framework around taxes and income that make this difficult

You still should pay your taxes on Bitcoin you earn. Tax evasion is easier, but not when your address is on the top of your project's website.

There's still friction. Do you know how to do your taxes on international income, CGT, discounting transfer fees, etc? There are services which will do most of that for you, but that's still time to export/import the transactions, ~$50 to get the summary, some more time to deal with actually putting that info on your tax return.

Realistically that's probably 3h of work in a year, but I'd probably pay a bit of money not to have to do it.

For small donations (e.g. $5) the transaction fee off Bitcoin can be larger than the amount.