Wot Milko sed.
And if even if they are replaceable it involves dismantling the laptop in some way, which is generally beyond the vast majority of people's ability (or confidence).
Whilst I have had a notebook that required undoing a flat-head screw before the battery could be removed, that was all it took, and most people could change a ThinkPad battery one handed with no prior experience/instruction.
(If there are devices where it's more complex than changing the hard-drive, that's probably a good reason to avoid that manufacturer entirely.)
Thinkpads are pretty much unique for that amongst mainstream manufacturers though. Other manufacturers are varying degrees of awful. Compounded by people wanting absurdly thin laptops.
Batteries (and other components) are just glued in place. It's sometimes possible to replace stuff but you really need to know what you're doing.
And obviously, from the manufacturer pov, this is a feature. They don't *want* you repairing or upgrading, they want you replacing. The logic of capitalism rather than the logic of *what would actually make sense for people*.
Shrinking enthusiast market. Probably 90% of computers stores around here got wiped out by the pandemic, supply chain issues, yadda. Most people can do what they need on a phone.