There are reusable and disposable plastic bottles. The disposable ones are of really thin plastic and crushed, yes. The reusable ones are put into crates and return to the factories so that they can be cleaned and refilled. You can actually look through the machine and see the stacks of crates in the room behind them.
Many glas bottles (e.g. for beer, water and more) are reusable, too. They’re treated like reusable plastic bottles. Disposable glas does not have a deposit on it. You take those to a bottle bank (? containers on the street you throw them into), which is emptied once every two weeks (not too sure on the frequency).
Cans are the only type that is always crushed on return, afaik.