Oh, you mean speed rating below factory installed speed rating. This is same in USA only that the tire shops won't install them for legal liability but if customer were to do this on their own.. they can at their own risk.
The V and Z rated tire quality really varies and what customer really wants. They got them all to cater to all types of customers. Cheapies V/Z tires have extremely hard sidewall and have their own quirks I had a Nexen... long lasting tire but really rough ride... and very noisy at low speed when worn but still quiet at highway speed.