system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why can’t people open their car doors when they drive into a lake?
gpt
Because the pressure of the water pushing onwards on the car is FAR greater than the pressure of the air in the car pushing out.             
In day-to-day lives, the pressure is essentially equal, so there is little to no imbalance in force, so it is easy.             

If you want to feel these forces, grab a plastic bag, put it over your hand, and try to hold your hand open (kind of like a claw) as you start putting your hand into a container of water (just make sure the water doesn’t spill into the bag). You will feel the pressure of the water pushing in.           
As an extra extension, if/when you let the water rush over the top of the bag, filling it, the pressure will become balanced again and it will be easy to love the bag.