There’s lots of factors that go into both monitor and mic design and execution that drives price of each. Couple that with zero available beltpack systems that do both transmission and reception and there is not a market driving the need for a combined product.

This isn’t to say that will not change. But at present, there is just not strong enough market drivers to offer combined product. Think of it as an analogy to putting effects directly into guitars. Yes, there was a small spurt of this but the overall market drive things in a different direction. It pops up now and again, but overall, not enough to to drive product development to mass acceptance.

What is your interest btw?