The sentence is:
Many people move to the city, because there are too few jobs for them in smaller towns. (It is a single sentence without context - taken from a 'complete the sentences' exercise)
It is already known that towns are smaller than cities; so what is the point of using the comparative adjective 'smaller' here?
Source: English for Starters _ Students' Book _ By: Julia Starr Keddle & Martyn Hobbs
Thanks in advance.