The only notable exception here is Apple with their absolutely bonkers RAM upgrade prices, which is why I would never buy a Macbook.
EDIT: I just HAD to look, MacBook Pro(ha!) by default with 16GB unified memory, it will set you back 400$ to go to 32GB, so more than 4x what Lenovo takes (64GB not even possible, of course).
I still think it would be beneficial for us to keep memory swappable at all costs. And if the connector is the problem, they should address that, rather than just accepting these tactics that _enable_ manufacturers in setting their own prices. I'm not saying they all do this, but there's plenty of them and Apple is the perfect example like you say.
As pointed out in the other comment, the true price at Lenovo for this upgrade is only $112.80 — not as good as you'd get with the DDR5 SODIMM, but it's actually cheaper than what Crucial supposedly charges for their 32GB of LPCAMM2, which isn't even as fast as what Lenovo includes.
https://www.crucial.com/memory/ddr5/ct32g75c2lp5xg — $174.99 for Crucial 32GB LPCAMM2 LPDDR5X-7500 — compare to a net $112.80 difference at Lenovo for an extra 32 GB LPDDR5X-8448MHz (Soldered).