Let's compare apples to apples. You're comparing what you deem to be the narrowest part of Tokyo with part of Amalfi which is most certainly not it's narrowest part.
You're also comparing very wide GT1 cars with a narrower Lancer, to put that into persepctive, the GT1 Tomahawk is roughtly 1/2 meter wider than the Lancer as
@Samus has already pointed out.
So here's a BMW V12 LMP on Amalfi:
View attachment 1139401
You could almost fit 4 GT1 Tomahawks abreast on that section of Tokyo, but you couldn't fit 3 BMW V12 LMP's abreast here without going off the road.
Bear in mind the pavement is not the road, how much wider is this section of road to those two lanes of Tokyo that can almost fit 2 GR1 cars abreast in each lane?
I'd say that section of Tokyo is roughly 1 whole car width wider than this section of Amalfi, that's 33% wider, that's significant.
Also, just to bear in mind, the BMW V12 LMP is also not as wide a car as the Tomahawk, it's over 10% narrower coming in at 2000mm, so almost 1/4 meter narrower.
Each to thier own, I'm just not a big fan of the new Tokyo circuits.