Yes. It happens in other denominations, too. But why assume the ones standing outside are the ones who only come once or twice a year? Seating is reserved only in Synagogues—not in Christian churches. The one-r/two-ers may have gotten there early enough to take a seat.
That’s one of the reasons I avoid church those days. It opens up a seat for someone that doesn’t normally go. It could be their day.
I know from years past how fast the Church fills up on Easter and Christmas, so I make it a point to get to Mass 15 minutes early AT LEAST so I won’t have to stand and to obtain a decent parking place. If I had to stand outside for Mass, I wouldn’t stay, because I wouldn’t feel as if I heard Mass. Also, the church has a simultaneous Mass in the Parish Hall to help alleviate the crowding of the church.
I suspect the people standing outside are the twice a year crowd because they wouldn’t realize that they have to get there early, and I don’t think they really care if they are hearing the Mass or not, just the fact that they attended at all is enough for them.