Do people typically shoot Foma just because it is cheaper?
Yes.
Sometimes, having a film that is substantially cheaper than the best film available, makes sense. I have taught a few people to use a view camera and to develop their film. In this part of the world, Foma Fomapan 400 4x5" film, is almost 50% cheaper than Ilford HP5+ or Ilford FP4+ 4x5" film. If you are going through a period of learning with mistakes sometimes happening, reducing your mistake costs by 50% certainly makes a difference. As for Kodak TMAX, people run when they hear the price; Fomapan 400 is 35% of the cost of TAX 100.
Currently in Melbourne these are 4x5" film costs of some of the more popular and readily available over the counter 4x5" films. Below prices are in Australian Dollars.
TMAX 100 $4.38 per sheet.
Ilford Delta 100 $3.23 per sheet.
Ilford FP4+ $3.03 per sheet.
Ilford HP5+ $3.03 per sheet.
Fomapan 100 $1.73 per sheet.
Fomapan 400 $1.54 per sheet.
If you were starting out in 4x5" photography, I have a hunch you would be picking one of the cheaper films to start your learning curve; more so when there is such a massive price difference.
Mick.