Possibly the $45 entry fee for 70 to 80 rounds of fun may seem a bit steep to some?
There are two reasons why round count is where it is.
1) IPSC stages are run in a 3:2:1 ratio of short, medium, long stages.
Max rounds for each of these is lower than handgun so for the same number of stages, round count will be lower by default.
2) range space - you need more space to run a good shotgun match.
There is a minimum distance required to engage steel.
Most handgun matches will have targets in your face and cram stages into shooting bays just to increase round counts.
This decreases the challenge and personally, I find that half the time I'm not even using my sights on these stages.
Lots of fun...
IPSC stages should be about the challenge of coming up with the best strategy/solution to the problem being presented to you, and then executing that strategy.
If the problem you are trying to solve is not falling asleep during the course of fire, what's the point.
You could offer a 500 round match for $5, but if its just arrays of 4 targets stacked on top of each other and a hose fest, I'd rather stay home.