We already have the golems in terms of mobile vehicle warfare, its just completely wasted in terms of potential. Adding tanks would just add more wasted potential because it’d have to be expensive and boring by design not to upset the “balance” of static siege being much cheaper, much stronger and spammable in any direction.
You’d have to change the siege completely for it to work. But its never going to happen. Anet doesnt have to suffer a rain of 10 arrowcarts on their way to the bank so they dont care.