Right, but what do you think the alternative is? There is limited space close to the entrance of the terminal, it has to be rationed somehow. Also what happens in practice is people take advantage. A trust-based 30s wouldn't work. Even with the current fees you can hang around Heathrow drop off and see the police having to move people along, check unatended cars, etc.
The alternative is not charging. JFK somehow manages. Yes there's traffic, but it keeps slowly moving.
There's limited space everywhere. It is rationed by people not wanting to be there. There's limited space at the baggage claim but nobody is charging you to be at the baggage claim.