Foot orthotics or supports are meant to improve biomechanical issues of the foot and to strengthen the biomechanics of the feet. There are lots of different kinds of foot orthotics and methods of making them for doctors to use and select from. A lot of people need and do gain from made to order foot orthoses while others may be helped by the simpler and cheaper mass-produced foot supports. What type is right for each person would be determined by exactly what is causing the problems and what the treating podiatrist advises is the best for that person. Many different foot orthotics have several design features and a good podiatrist will attempt and match those up to the requirements of the individual. If that is not done properly, then there might not be any improvement in the issue.
Foot orthoses aren't without their issues. If they are not the right choice for the individual, they'll likely won't work. You are also restricted by what shoes you can use, in that you have to be able to fit them into the footwear and there might not be enough space. There are also types of footwear, for example the flip flops which they simply can't be used in. This may present a challenge in hotter places that make closed in footwear needed for foot orthoses uncomfortable. There are options, as an example, the Archies that have a foot support built in. The shape of the arch supports in these flip flops are like what you should get in an over-the-counter arch support, but probably not as good as what you would get from a custom made foot orthotic. Using these do give a helpful option to foot orthoses, depending on where one can wear them and the character of the biomechanical problem. If you do need foot orthoses there isn't any harm in trying these types of alternatives or raising it with your treating doctor to see what they believe.