Why doesn't Ketchikan, AK have a control tower? Why doesn't Ketchikan International Airport (PAKT) in Alaska have a control tower?  The special flight rules applicable to the area (14 CFR 93 Subpart M) seem to make it clear that traffic management is an issue, focusing mainly on being in contact with the Ketchikan flight service station when it is in operation.
The now uncommon situation of an On-Airport Flight Service Station as noted in AIM 4-1-3 would seem to be in force here, but in Ketchikan, it appears that under the SFAR, seen in Ketchican FSS Information, participation is mandatory.
With mandatory participation, what separates Ketchikan from an airport which would normally be served with a control tower?  Does it not quite qualify based on traffic?
A tower can only control what it can see, visually or with radar. The traffic in that area is at low altitude and landing or taking off many places that are not the central airport, much is VFR and not inside the space of a class D tower.