The question to me then is how exactly is the service is determined - are providers explicitly asking for new batteries (or even new HA) or is it that at 3 years it’s a given that the battery has declined to the point of needing replacement per the manufacturer diagnostics?
This conversation over the last few days about the lifetime of the rechargeable battery would make me hesitant to suggest a rechargeable for someone with limited income and no/minimal hearing aid insurance that might need their hearing aid to last 10 years or more with good care (that was me as a college student in my 20’s). Knowing you need to get your hearing aid refurbished at year 3 to get the best lifetime out of your hearing aids is another hurdle. This is not obvious in any of the literature I have seen and if you don’t see your audiologist or fitter every year it could easily be missed until the battery and aid are out of warranty.