A hearing aid or cochlear processor without a telecoil is like a car without air conditioning. You don't need it all the time, but when you do it's invaluable!
The telecoil is what connects your hearing devices to all the technology mandated by the American's with Disabilities Act. That is referred to as 'communication access'. Transmitters should be installed in all performing arts centers, in auditoriums, in meeting rooms, churches, etc. However, the ADA also requires that people ask for access, so it forces us to know what we need in order to be able to ask. Consequently, many places get by without providing access. In regions of the US where HLAA chapters are active, you will find far more places with this technology because people have requested it, educated about it, and advocated for it. It's a vicious circle, but the reality is, we who have hearing loss deserve to be able to participate in society just as those who need curb cuts for mobility access do.
It's a terrible shame that the people who sell hearing aids do not educate their 'customers' about the options a hearing aid can provide. There has been a huge push to sell BlueTooth features that add considerable cost to hearing aids. Telecoils add less than $15. BlueTooth is wonderful at connecting wirelessly to some audio devices, but it doesn't work in venues with public address systems. The reason, in a nutshell, is that in order to connect with a BT hearing device, the speaker/PA system has to have a microphone that interacts with each specific BT device. Imagine a presenter having to wear 50 microphones because there are 50 people in the arena that need to connect. One transmitter, attached to a PA system is all that is needed to connect to all the telecoil equipped 'receivers' in the arena.
Telecoils don't matter until you know what they can do. Ask the audiologist you are working with about them, and insist that they let you try them before you buy hearing aids.
When I researched my Phonak hearing aid model on-line, I saw that they came with telecoil but at my final audiologist visit I wanted to verify it with her. To my surprise, she said that telecoil is an *option* with my HAs but **I needed to ask for it up front**. She acted like there aren't many venues around here using the technology, which may explain why she didn't mention it initially, but she also said I can exchange mine for the same Phonak HAs with telecoil and my trial period will be extended as well. I just want to echo what Julie said here - ask your audiologist!