Yes, they work just fine outdoors with GPS ... which is exactly the way most drone flying is done.
They would always be working unless your drone has had a very rare hardware failure.
But if you are wanting to land on a helipad at sea, do you...
I was with you up till you said this, betraying your false ideas about the degree of freedom enjoyed in other countries.
Most countries are at least as free as yours, quite a few have even more freedom.
Except that being close to anything never initiates RTH.
It just doesn't happen and never happens.
Being close to obstacles might initiate obstacle avoidance or in could initiate a crash, but that's all.
Whatever the cause of your RTH was, it had...