If dealer opens. second seat needs to be at least somewhat careful taking actions such as doubling or overcalling. That's because third seat may theoretically having "everything" (not held by first and second seats), leaving partner with nothing.
But if left hand opponent opens, partner passes, opponent's partner passes, then right hand opponent is limited, meaning that fourth seat can double or overcall light. That is, s/he can "balance" with a king or so less than in second seat by "borrowing" it from partner, who clearly has something.
Likewise, I was taught that a fourth seat person could open a major suit with about a queen less than in the other seats, because both opponents (as well as partner) was limited. That is, while one needs something like (s)AQxxx (h)Qxx (d)xxx (c)Ax to open in the early seats, it would be ok to open with (s)AQxxx (h)xxx (d)xxx (c)Ax in fourth seat.
Do most experts feel that way? And how would they feel about opening a junky five card major in fourth seat with 11 high card points, something like (s)97532 (h)KQx (d)Qxx (c)Ax?