It's a good observation to make, I remember when in the early 80's the opposite was happening. My father was approached to sell his '72 GTS and 70 Mangusta to ship to the US in 1981 while at the factory for repairs. Ended up keeping them and selling them in Italy later on. For quite a while in Italy DT's in general were frowned upon as were the Bizzarrinis and the Iso simply due to the engines and their hybrid nature. Now the appreciation in Europe in general is far higher than in the US, these cars have been re discovered by the same people that considered them second rate when in production. The more original down to the Leatherette interiors, the more interest and price these cars generate out there.
Vey interesting, thanks for sharing.