Maybe the connection is more sophisticated and includes back flow preventers, no air accessible mixing g, gas traps, etc....
I've been contemplating the absurdity of this given the challenge in the thread.
My position/statement comes from watching the contractor connecting pipes and a conversation with the GC during the final walk thru. My statement parallels his statement about all drains in the house going to one spot and what I saw.
Maybe he misspoke and I misinterpreted what I saw??
It is rather rural here, so maybe that's the logic?
Sewer/storm connection aside, I'm positive about the French drain and Storm, so my statement about garage drain and street gutter still holds.
My garage runoff ends up in the Storm collection regardless, with or without a garage drain.