That is the key, meaning durability. While RDS have only been around a relatively short period of time. Scopes etc. have been around for quite a while. You would have to assume that they have picked up a few things along the way. And for what it is worth I have had a Kahles Helia RDS of a 45-70 lever gun for a while. It kicks significantly more than any of my shotguns, at least with the rounds that I run through it. No issues to date.Yes but there are other factors. Shotties are heavier. On pistols optic is in line with recoiling part as it moves, on shotgun optic sits above the path of bolt's travel.
In recent past there has been one specific longarm with a reputation for being hard on optics, and that is a SCAR. The common explanation was a specific recoil impulse or momentum because that rifle uses a very heavy bolt carrier, even though the perceived recoil is rather mild.
I think there are too many variables to be certain about anything. I am just glad we have durable optics these days.