It would be nice to get rid of the batteries, but there seem to be downsides to each of the alternatives currently.
Solar scales like the one from MUJI seem to update measurements slowly. I haven't seen one that looks like it is responsive and likely to work for a lot of weighing tasks. Seems like this may be the best option for a manufacturer to innovate - bigger solar array, and a super capacitor to hold a good charge.
Mechanical are pretty classic and durable, but you choose either capacity or precision. I haven't seen even a 2kg model that has 1g precision. More like 20g. So not very useful for home baking. Perhaps fine for general portion control. If you go this route you will probably need one small precision scale for fine resolution and a larger one that can accommodate 5kg.
Kinetic scales from CASO seem like a good option. The main criticism seems to be a short usable time after charging. It would stink to be 5 ingredients into a baking recipe and lose power midway through the next ingredient. It would also be annoying to keep stopping to charg it. They also seem to have slow updates when the weight changes like solar models. This is probably to reduce power usage. I think these are fine for occasional use, but not if you're using a scale 3-5 times per week.
My personal solution has been to use a commercial scale that has a rechargeable battery built in, as well as a power adapter. I keep it plugged in, on our kitchen counter, and I use it nearly every day. After 10 years now the battery doesn't hold a charge, but it works fine while plugged in. I could replace the battery, but don't need it.
If you really want BIFL then it's probably best to check out restaurant supply stores to see what they're selling. At least in the US the scales from Edlund are well built and reliable, and for digital you can get a good one priced under $100. Taylor are lower quality and not as reliable, at least for the affordable models.
For mechanical i would expect to pay $100+ for a good small one with 10g precision. To get more precision the dials need to be pretty large, so this would be a trade-off.