Simply because there are serious advantages to both power sources. I’m old enough to realize now that there are many HA users who never have used a disposable battery. For many their first HA used rechargeable batteries and they know nothing different. On the other hand there are HA users like myself that have used disposable batteries there whole life and don’t do a lot of streaming. I’m not here to push one battery type over another. But if Phonak coming out with the Lumity thinks its the future offering new aids with rechargeable batteries only - then company is making a major mistake.
For years all I’ve heard is rechargeable batteries save HA users the cost of buying disposable batteries year in, year out. Well that’s true except for the fact that I can six months worth of disposable batteries (size 13) for say $20 bucks, give or take. So let’s just throw out the completely false cost factor. Especially since HA manufactures charge user the cost of a battery charger along with the higher cost of a rechargeable battery (maybe two) that greatly exceeds the cost of disposable batteries for say three years.
Then next we get into environmental issues where HA manufactures claim disposable batteries are bad for the environment. As if HA manufacturers give a hoot about climate change, toxic materials and clean air. Give me a break. I’m more concerned about water disappearing on the West coast and Florida being underwater in twenty years than if some disposable batteries end up in a dump some where.
When you finally cut through the weeds a lot comes down to some one’s hearing loss level. Someone with a mild loss might just be perfect with rechargeable aids. On the other side of the coin someone with a severe hearing loss might like the power provided by a 675 battery. Then you have the group (large group) that does a lot of streaming, phone calling, etc., that drains a battery faster than normal. What ever “normal” is. That’s when rechargeable batteries come in especially for the smaller batteries such a sizes 5, 10, 312. Makes all the sense in the world to recharge these small batteries, if you using your hearing aid for more than just general aid amplification.
But when you get in the size 13 or 675 battery there some serious advantages to going disposable. A user doesn’t have to worry about putting aids in a charger at night. A user of larger batteries doesn’t have to worry about power outages or packing a charging kit when traveling. If your in a meeting and your aid battery dies, you just excuse yourself, find the nearest private area/rest room and put in a fresh battery. That is if you carry some spares with you.
Personally I wouldn’t want to deal with going some where knowing my rechargeable battery might die while I’m at a restaurant, movie, date or what ever. Sure there is a timing factor here but still its a question mark if someone rechargeable battery is going to last 18 hours, 20 hours or 30 plus depending on daily usage and streaming. With a disposable battery I know I have 7 to 9 days operating use with a size 13 battery and maybe two weeks with a 675. That provides piece of mind.
I’ve read a ton of posts on HT about chargers not working properly or HA users upset their regaragble batteries are not charging correctly. Over time I think general recharge issues have improved, but still I read complaints from time to time.
In any case HA manufactures need to offer both types of batteries to the buying public since different people have different needs living with a hearing loss, Hopefully Phonak realizes its better to appease everyone by offering battery options. Excluding certain groups or those with a severe to profound hearing loss is not what we we call “consumer friendly”.
But simultaneously, I praise the hearing aid manufacturers, when credit is due…
Your rhetoric, speaks volumes of whom you are… Perhaps insignificant comes to mind, as we say in Scotland, “Awa an’ bile yir heed”… Of which there are many interpretations, but I will keep mines to myself… Take it easy, Cheers Kev 
My beef is with the conclusion jumping and logical fallacies. Such as the premise that if the companies don’t make what some purchasers want, then all sorts of unproven speculative motives must be true.