I said VT4 not VT5, and I gave an estimate 40% of Bridges in general. VT5 is a light tank that is a different category of Tank. If you want to count that then you start with Type 59G, T55, CV90120T, PL01 concept, FNSS PT Pindad Modern Medium Weight Tank.
In summary how many MBT weigh in at under 40 tons????? one T64 and some upgunned T55 variants that's it. and even then they are leaning to 40 tons class.
Sure there are a few in the 40 ton weight Class T84, T90, Type 10, PT91,Type 96, T72... but other than the Type 10 ( and some argue that as a light tank) most of these are the base weight without armor add ons or older versions.
So the problem is not unique. All MBT happen to fit in that excessively heavy category including VT4 and Type 99 and Type 96. Both Versions of the Arjun the Mk1 at 59 tons and the Mk 2at 68 happen to fit this to.
Arjun was always a limited order, the Fact the T90S Bhishma was being Ordered in massive numbers alongside small batches of Arjun was pretty much proof that the Indians never meant to make it their main line MBT. They ordered something like 1200 units of the Russian tank.
.