You're comparing top names with run of the mill engineers maybe, which isn't fair.

And maybe you need to discover talent rather than buy talent from the previous generation.

AI researchers at top firms make significantly more than software engineers at the same firms though (granted that the difference is likely not an order of magnitude in this case though).

Unless you know something I don’t, that’s not the case. It also makes sense, engineers are far more portable and scarcity isn’t an issue (many ML PhDs find engineering positions).