The question of whether this trope is Truth in Television is a complicated one. It certainly can be painful to wear a corset, but it doesn't have to be, and isn't always.
In general, there are four factors at work in whether wearing a corset is painful or not. They are
- The design of the corset.
- How well it's fitted to the person wearing it.
- How tightly it's laced.
- How accustomed the person is to wearing that style of corsetry.