Burying high voltage power lines presents several technical challenges on its own - the type and thickness of the insulation had to be able to withstand the dielectric stress which is normally solved by using enough distance between the wires themselves and the ground for the typical high voltage power line. Another problem is increased capacitive load due to the higher capacitance of the lines which causes problems/completely makes the switchgear to not be able to perform switching/breaking operations. Capacitive load then needs to be compensated to improve the networks power factor, cos phi. This is typically done by introducing expensive equipment to the network configuration like shunt reactors or static synchronous compensators. It is also typically more expensive to have and maintain a underground cable than an overhead power line
I just think that the term transformer is overloaded with several meanings - electrical transformer, the cartoon, a transfer function in a NLP neural network and I have heard it used in ETL applications for the transform function. Not fields that are closely related, but still it might result in semantic confusion nonetheless. Similarly term translation has a completely different meaning in mathematics than in linguistics, e.g.