G or L (for lobby) followed by 1 isn't uncommon in the US.

> Confused me when I visited USA

It's applied inconsistently enough to be confusing for natives too!

I've just come back from the vacation in the US, and my experience was: when the hotel has G or L for the ground floor, it still has 2 for the floor directly above it. "G or L followed by 1" never happened to me.

It's the consistent inconsistencies that causes it to be less confusing. It would be really weird to go from someplace very orderly to another that is haphazard.