Is paying 50 dirhams to a worker who arranged for no parking tickets to be issued, in exchange for my exemption from parking fees, considered a bribe? And what are the consequences for me if it is considered a bribe? And must I pay the fees in the future?

It is obligatory to pay parking fees to the owning authority. Whoever has not paid must do so, unless there is an official exemption. If a worker performs a legitimate favor that is not part of his duties, he may be rewarded. However, if his work falls within the core of his job, then giving him something falls under the category of gifts to employees.