Something else that may vary is whether a car has a delay when you lock it. I hired a car in the US once (I'm from the UK) and there was a several second delay

Something else that may vary is whether a car has a delay when you lock it. I hired a car in the US once (I'm from the UK) and there was a several second delay from the time of pressing the fob to the car actually locking. Because I sometimes check that the car is locked by immediately operating the physical door handle, I was initially convinced that the locking mechanism was broken.