Glass looks like a thin film of transparent plastic sheet

[joseph]

Nope, only if you use Subsurface (that’s why the IOR is Subsurface IOR, not IOR).
https://docs.blender.org/manual/en/latest/render/shader_nodes/shader/principled.html

Edit: ok I’m actually wrong, it does use Fresnel, but not very well:

Specular in Principled BSDF is (still) broken?

so specular is only broken at low/high roughness values? how does it compare with Maya at middle roughness values? if this is the case then I’ll be clamping my roughness maps between ~0.1-0.9 to avoid those values