I'm pretty sure they don't check. "May" now means "legal told us to ask you to PLEASE don't do this".
Related, I often see people trip on the sense of MAY in RFCs (https://www.ietf.org/rfc/rfc2119.txt), because in everyday use it has become "passive-agressive must".
edit: I'm ESL so might be reading way to much into this.