I haven’t read all the responses, but I think if the priest explains why they are there and why it is better to stay through the end of mass, it could help make a difference in the number of people who leave early.
As a cantor and one who freelances all over my diocese and other dioceses, I’ve noticed a difference in city-dwellers, town-dwellers, suburb-dwellers and country-dwellers.
I currently have three different continuous cantor jobs - Two in the city in one diocese and one in a town in another state and diocese. Then I also have my own parish which is in the suburbs, a parish I attend in a rural dwelling on my family’s vacation property and then my various freelance cantor jobs in the city where I currently work, other churches within that diocese and then different dioceses and states.
Most of the city-dwellers walk to mass. The one parish I usually work at doesn’t even have a parking lot. You have to find parking on the street if you do decide to drive. I’m either cantoring up front or from the choir loft and I have a very good vantage point from both positions. Right before mass, it’s not that filled up, but there is a good number of people. But it really fills up by the time the processional hymn is over. I don’t look out into the congregation when I’m cantoring and no matter how many time I do this, I’m always surprised to see how packed it is by the time the hymn is over and I actually look at the congregation. The regular parishioners don’t usually leave early. They will stay till the end, although you do see people leave once the recessional hymn starts or after the priest passes their pew. There will be a few people who leave right after communion, but it’s not actually many and it’s usually tourists or visitors.
In the town parish where I cantor, it’s almost the same. There is a parking lot, but because it is a very large and active parish and many of the masses are pretty much back to back, you can’t get there early unless you walk to mass or find parking on the street.
In some of the suburban parishes, from the one I grew up in, the one I’m currently in and then others where I freelanced, I’ve seen people act like the NYC commuters on the train ride home from the city. I used to ride the train from Manhatten once a week and would laugh at how ridiculous people acted. They wanted to be the first ones out, then run to their cars in their suits and heels and be out before the rest of the people caused a backup. I admit, it is horrible having to sit just to get out of a parking garage and parking lot, but these people looked so funny. At these churches, it looks almost similar. A herd of people rush to the doors… something you can’t miss because there are so many. They rush out like those NYC commuters and I remember a few times looking out of the window and seeing people literally running or jogging to their cars, pulling their little ones in stride.
In the country parishes I’ve attended, everyone knows everyone and it’s rare that people are late and even more rare that people leave early. I think it may have to do with the fact the church buildings themselves are small and because they do know each other, you can’t just slip out without being seen. Also, if someone does leave early, after mass, you hear people asking each other if maybe there was something wrong because it’s so rare that you see anyone leave before the final hymn is finished.
Anyway, those are my observations. I think for those parishes which do have the mad rush of people leaving after communion, the priest should make mention as to why it is important to stay and maybe, in a humorous tone, talk about how silly the people look when they do rush out and how they look like a herd of cattle or a bunch of high-strung city workers rushing to their cars to get out of the parking lot first. It could get those people thinking and maybe change their ways.
Of course, there are always exceptions. I’ve had emergencies myself where I’ve had to leave early and I do understand those who are in positions due to emergency work, sick relatives, etc.