I was thinking the same and concluded that creating lenses back then probably involved manual work, and were more hand made in general. So the distortion we're seeing is probably due the higher degree of imperfection in the lens sphere shape of the old lense.

But theoretically this could be corrected further using software. If you correct one picture manually, and used the same distortion as a reference for other pictures. Maybe...

No idea if there is software like this anywhere.