Depends on the venue... I deal with a lot of audio installation companies and they tell me that these are put in place mainly by the local council when venues come to re-new licenses. Now the venue may or may not be responsible for causing a nuisance with sound levels but it's not always the case. Out of the 100 or so 'Venue gigs' I played at this year, a good majority of them had SPL meters. Most we were able to work with, keeping below the limit. Some places we just bypassed altogether on willing authority of the management.
There are places where these things just do not work. Last year we had a venue, fairly posh affair where we were to play in the bar/lounge area. We got there and set up only to find that the limiter that we had not been told about on our pre-gig meeting at the venue was tripping out with the background noise of the bar...... needless to say we couldn't play and had very angry Bride and Groom. We pointed this out to the management who had to take full responsibility and moved the band into the Dining hall to play. Some venues!