What's the purpose of limiting parking to three hours?

There are a few things I have trouble understanding. One such thing is parking regulations in zones where you can park between 06.00 and 22.00 (for example). Often you will see areas get empty after they introduce parking fees, simply because people don't want to pay for parking. But then you have those people who are happy about it, because finally they are able to find free parking lots easily. So, imagine that you are traveling by car from Vienna to Budapest and you want to park your car at Bikas Park for the entire day. There is just one slight problem, they limit the fee you are allowed to pay to three hours. Isn't that just stupid? If you are a tourist, you don't want to return to the parking after three hours to extend your parking. You want to either have a solution in which you pay for the time you stay at the parking lot, or you want to be able to pay for all possible hours at the same time.

Instead, it is a chaos and you end up not parking your car there at all because it is a bad solution for you.

There are times when a three hour limit is logical...

There are some situations in which I find a parking time limit to be useful. It is, for example, in very busy areas where you don't want people working in the area to leave their car there for the entire day, which helps temporary guests who only want to park for 30-60 minutes find a parking lot. After all, if people could park there all day, it would be packed early morning buy people working in offices downtown, and tourists and other people would be unable to find parking lots.

But, if you have large streets and parking areas outside the city center, normally entirely without cars (due to the parking fees), then I don't see any purpose at all for creating a maximal parking allowed time...

What do you think?