Comment by kubanczyk

Did you try that? These "remote" jobs that OP is describing filter you out instantly because of geography, so there's nobody to speak to about B2B contract.

These that did not filter me that way, offered both: either regular employment or B2B. These are truly rare, say 2%-5%?

My guess is that in countries like US, B2B contracts for individual SWEs are considered something very special and snowflake'y. Like they fully expect you to disappear three hours in, never to be seen again.