Yes they do.

This one is typical, it was about 30m down from where I was standing, and maybe 100m before the start of the last little steep bit before the KOM. There would have been 1500-2000 people up there at most, and I'd lean towards the lower number.

There have been heaps ppl more in the past, with cars parked all the way down nearly to the bottom corner and elbow to elbow on the side of the road. I've been to about five of them and it wasn't the biggest crowd I've seen, not even close.

Like I said though, I didn't go to the start so I have no idea what it was like in the town.