Learn English – What do you call a person who usually talks about a matter he/she doesn’t know much about

If you want negative connotation

How can you be so relaxed?! You just can't be bothered can you?
You're really can't be bothered! I'd study harder if I were you!

which means not to care with indifferent attitude.

Something which is neutral in connotation

How can you be so relaxed?! You're such a non worrier! You never worry about anything.

Another alternative is

How can you be so relaxed?! You're so laid back! You never worry about anything.
You're really too laid back! I'd study harder if I were you!

which implies very easy going.

I don't think there is a special term for that in English, but if we're talking about public places like shopping malls, restaurants, hotels etc., you could always refer to people who park their cars by themselves as self-parking customers:

Valet parking is a parking service offered by some restaurants, stores, and other businesses, there is Valet Parking in all parts of the world. In contrast to "self-parking", where customers find a parking space on their own, customers' vehicles are parked for them by a person called a valet. This service either requires a fee to be paid by the customer or is offered free of charge by the establishment.