I think it’s the same honestly. I let mine collect for a full 24 hrs for the commons, usually end up with about 10, depending on when I do my daily collection and when the incidents spawn, but if I don’t get ~10 when I do collect a few more pop up not long after.
Uncommons I will usually get between 2-5 show up. Rares I have seen 0-2 in a day, I don’t recall ever getting more than 2 appear in the same 24 hour period, but I usually collect Uncommons and Rares when I see them to snag extra fps on the rare occasions they drop.
So it seems based on my observations we get about 15 a day. I think some folks collect them as they pop up so they feel they get less, but if you let them build up for 24 hours you’ll see just how many you get. To do that without losing any is to collect every single one you can find when you collect from your Town Hall and use that as a timer. The following day do a few rounds around your city 10-15 minutes before your town hall collection if you can and see if you find a difference.
The players claiming to not finding many Incidents could also just be getting Road tile ones that are harder to find unless you are actively seeking out each one. I found if you go into the “Move” mode and drag a large building around your city you can “see” through the buildings to the road tiles and find those ones a bit easier. Turning on animations before doing rounds helps as well since the cars or people will build up behind the Road tile incidents.
Hope that is informative and helps a bit