Why do they put seam tape on slide roofs instead of caulking

But, caulk seems to be used on the sides of the slide where the tape ends. Maybe because it's vertical at that point for some reason?

On my trailer there isn't any tape on the slides, only caulk. But the flap is only a weather seal to keep out rain or snow. It is not the seal to keep cold or heat in or out. So, when the slides are out the flap is 2-3 inches away from the caulk at the inner seam of the rubber roof and rests on the rubber roof material. When the slides are in the flap passes over the caulk on the outer edge of the roof material and rests on a metal edge of the slide wall. The caulk has never been effected by the flap. And when we set up camp I check the flaps to be sure they are flipped outward and if not I use the awning pull rod to pull them out, Takes about a minute for 3 slides.

Previous rig had Eternabond over the joint where the slide wall met the rubber. Never had a problem with the seals NOT flipping. Seems to help them flip.Not so with current rig.

Slide moves through rubber seals.caulk would be a mess.

Did you ever see a perfectly flat and even bead of caulk? The seal has to seal against it and tape is flat smooth and level. If the top of the slide is..