The big container terminals in most of the European harbors were before SOLAS already equipped with cranes that could weigh each container. However, that was more of a necessity to protect the cranes against containers that weighed more than the lifting capacity of the cranes could handle and not so much as to verify the weight against that mentioned on the bill of lading.
Southern Europe, with a large number of smaller ports, is a problem area as this is also the case in most parts of the underdeveloped world, India being the nice exception. Yes, it costs extra money, investmentwise but also for the weighing station fees, but the weight verification will lead to additional tonnage being reflected on the manifest, which will exceed the amounts charged for verifying the VGM on exports. Shippers will be careful declaring the real weight once knowing that containers will be left behind or to avoid penalties.
In my port (Aden), we will hardly be able to look at this issue because we are already not an efficient port and that will add to our challenges.
This picture shows the situation in 2016 and it seems that worldwide only muted progress is made with the implementation of the SOLAS requirement, also in the US. In the US, a number of ports including Long Beach, Los Angeles, and Virginia refuse to install new equipment at their terminals, arguing that existing weighing procedures already comply with SOLAS. That was also the position of the US Coast Guard, as expressed in a U.S. House of Representatives Hearing, in April 2016.