Playing bar pool there is a convention that the person who won the last game owns the table, and anyone in the bar can challenge them for the ownership of the table. The challenger pays for the rack. Winner of the game keeps ownership of the table, sets the rules for the game played, and ... next challenger up. It is a great fun game to play to get and keep ownership of the table against all comers. You can get some quite good pool games this way. You can play world class players for nothing more than the $1.00 cost of the rack -- an awesome cost, even if you lose! If you want to play with some friends, well, you'll have to beat the owner to get on the table -- get your quarter and your friend's quarters up!
In the bar environment, watch out .. sometimes there can be some funny business going on. It can help to sit back and watch what is going on before getting your quarter in the rack. Find out what is really going on with that table. The quarter isn't so much the issue as the time you spent waiting to play that table when something unreasonable is going on. When you could have walked out to go play pool at another venue instead of sitting around an hour to play and then ...
However some people think they really own a pool table because they won the last game on it.. and that no one else can play on it.
In other words, some people who are jerks who do this. To the point that the pool table in a bar is sitting idle because no one can play pool. For example, some friends who want to play pool -- with each other -- not with some jerk, and they can't. In other words, the table is not making the bar or the amusement operators any money at all because of the actions of this person. As a coin operated amusement, the person who puts money in such a device has all the right to use it as they please. If this person hassles you, tell the "owner" politely that you are going to be using the table, but that they still retain "ownership" of the table when you are done with your game. As a player who has been both sides of this, it is a polite way for two different groups of uses to get use of the pool table.
If someone walks up to the table after you put money in it and tells you they own the table... Who knows if they really do or not, or they are just somebody trying to geta free game from you. They need to tell you AHEAD of time that they own the table. if they don't, you don't know bupkus about them. If they are insistent, have them pay you your money back, and they can have the table. If they persist, or act like jerks, or hassle you -- get a bartender or other staff. That person is trying to stop you using an amusement that you legally paid for.
Another form of bar pool scum? They put their quarter in the queue for the table, win, and then switch up the game. Change it to 9 ball from 8 ball. Require a bet to play the game. Suddenly require people to play doubles -- and you don't have a partner. These folks are real scum, they are trying to force people off a table so that they can play it themselves. As a courtesy, don't act like those people! Certainly you can ask if people want to play doubles, or ask if a challenger wants to play for a drink ... and how much exactly that is going to be! Demanding it of peeople who have been waiting an hour on their quarters to play a suddenly different game is wrong.