Ya, I don't quite understand how they knew op would be unlocking their car at that exact time. I think they may have jimmied the lock or something, and was already stealing stuff before op even showed up.

Yes

And annoys everyone around you.

Yeah but it's safer than unlocking it...

OP probably would have turned the alarm off after they located their car. The alarm really isn't that annoying unless it's going on for a long time.

*crowed

Thing is those remotes only have a short range usually, often around 10-20 meters even with a good battery, assuming OP was walking at a normal pace that's hardly enough time for someone to steal stuff unless they were right there at the right place at the right time or as someone suggested they were already into OP's car before they hit the remote.

Unless OP used their phone to unlock their car. Usually the range for the phone remote is pretty long.