We should not bend over backwards for people not following the standard.

Build tools that follow the standard/best practices by default, maybe build in an exception list/mechanism.

IPv6 space is plentiful and easy to obtain, people who are allocating it incorrectly should feel the pain of that decision.

I can't imagine why any ISP would do such absurd things when in my experience you're given sufficient resources on your first allocation. My small ISP received a /36 of IPv6 space, I couldn't imagine giving less than a /64 to a customer.