Yep. The rules are very unevenly enforced. Also, that listing isn't an "Amazon Merch" listing, nor is it being fulfilled by Amazon. It's an independent seller.
Also, it's Ironfoot's design, being pirated. Which Amazon will refuse to do anything about.
Amazon Merch listings, in particular, are held to a higher standard, since Amazon is both the maker and the seller -- which means that they have some culpability for selling merchandise that infringes someone else'e (e.g. Piaggio's) IP.
But
even then, there are definitely Amazon Merch listings that include the word "Vespa", and when I pointed this out in my ongoing discussion with the nameless fuckwits at Amazon, I got... silence.
And then to make matters worse, when someone pirates your Merch design and lists the same design with the same title and same description
on Amazon Merch, Amazon will do sweet fuck all.
So, yeah.
It's not a case of "somewhat flexible use". It's a case of the playing field not being level or even obeying the laws of physics.