Does radio room in Fallout Shelter always attract the same kind of low stats dwellers?
Solution 1:
The Radio Studio (wiki link) has nothing to do with the quality/level of the dweller that shows up. That's a random attribute, with of course the higher level/legendary characters being much more rare. What the Radio Studio does do, however, is increase the chances that a dweller is attracted to your vault. Basically it just speeds up people coming to your vault door. That's really it. (Well and it increases vault happiness too, but that's unrelated to dwellers showing up.)