Super common, basically pool halls seem to fall into two categories... "the owner shoots and gives a shit" or "the owner is not a player and just doesn't care". The first type has uniform sets, the second type will usually have several bad sets mixed with barbox balls or another brand.
Our league hall is the 2nd type and one set has a barbox cue ball mixed with the regular balls. I absolutely hate that.
So you're saying that when ball goes they should change the whole set?
Local room i play at has 32 tables, the manager told me they change at least 12 cues balls every 3 months because it's the ball that takes more hits and gets damaged fastest, then comes the 1 ball which they have to change about every 6 to 8 months because it's often the head ball and gets smashed a bunch, the rest get replaced as needed. Everything they replace gets replaced by a new centennials ball, but i can't see any room tossing a whole set in the closet just to replace one ball.