Well, for like 3000 years they were essentially restricted to a tiny island, they could have reached industrial level technology, but where are they going to get coal? and oil? without reducing Themysceria to a blighted wastland of mining? I mean technology requires lots of resources... and electricity doesn't come from magic (...I suppose it could with them, but then where does the magic come from? from all the evil magical leaking from Doom's Doorway/Pandora's Box? do they literally pray/meditate for power?) And they are like several thousand immortals who are for the most part in harmony with nature... They don't need trains or cars... ...though they should have been capable of inventing bikes... I don't think there's enough of them to really justify a communications network (maybe a telegraph)...