As others have said, they do this on purpose. It's the same with memory. I'd probably switch from a Pro to an Air if I could get 64gig ram (for LLM work) but they'd rather charge me $4800 instead of ~$3200 (guessing the price given the top end 32gig Air is $2800)

It's frustrating because I'd prefer a lighter device. In fact, even the Air isn't that light compared to its competition.

I'd happily pay +$500 ($5300) for Macbook Air PRO if it was effectively the same specs as Macbook Pro but 1.5lbs lighter.