An owner doing a DIY repair can take the time to remove the fender well but yes, it wasn't normally done by the mechanic. Many years ago I had a 1971 Catalina that I bought from my dad; during his ownership the blower motor was replaced, and the mechanic who did the repair did cut a hole in the fender well for access. If I remember correctly, the fender well actually had a circular mark pressed into the steel to show where to cut the hole.
By the time i finally junked the car, the metal patch they screwed over the hole had rusted out.
