Lloyd I worked for Westone; the inventors of in ear monitors, for 5 years.

Most live sound engineers still want a larger microphone capsule in front of a singer. Head worn mics don’t offer that, on purpose, for discreet (read: less visible) use; largely for drama.

In ear monitors, on the other hand, offer the engineer and musician many benefits. I will admit it is a bit of a learning curve for some to learn to sing on key with in ear monitors in place, present company included.