Why we use analogue
I work in touring theatre. We use still use analogue radios for two reasons: Firstly, we can't afford to upgrade (margins in the arts are extremely tight, and often charity-funded, so we have to justify every little expense); secondly, analogue transmissions may occasionally fade out a little with weak signal or inteference, but they won't fail completely like digital radios do.
Anyone who has a DAB radio or Freeview TV in an area of weak signal will know what I mean; instead of static, the signal stutters or vanishes completely. We can't take that risk in the middle of a climactic aria!
I don't see many productions or theatres moving to digital anytime soon, even if they can afford to.
Aside - for the same reason, we use a new set of alkaline batteries for each actor's transmitter at the start of every show. I keep getting asked why we don't use rechargable batteries; we can't afford to let them run out during the show.