Back in my bar-tending days we always told the door staff (bouncers) to slow down when checking IDs early in the evening, just to get a line going. It works surprisingly well for drawing in more customers.
Totally tangential but follow-ups on that psychology:
* some people would walk in and see the still mostly-empty bar and get fed up that they waited in line for "nothing". This was surprisingly few people though.
* some people would ask and buy just about any explanation - "oh that guy is new and still learning", "we had someone get in on a fake ID and got a fine the other day so the guys are just being careful" or whatever and the people would be glad they got in early to get a good spot.
* sometimes we'd slow down the bar staff a bit too so that there was a line to buy drinks and people were happier that they had to wait in line again - confirming their bias that they must have gotten in at the start of the rush.
* some people were wise to the scam and everyone who called us on it thought it was great. They often offered to have their buddies come through the line a few times in exchange for a free drink.
* for some reason when you let your buddies, regulars and off-shift staff cut the line and get in quick, the rest of the folks seemed more willing to wait in the line.
tl; dr - group psychology of humans is wierd.