How telepathic are Romulans? Perhaps they've lost this ability over the centuries after their exodus. Telepathy played a big role in the savage nature of pre-Surak Vulcan. Maybe without telepathy, the Romulans have had an easier time in conquering their savage heritage.
Or, perhaps the telepathic Remans figure into this somehow.
One thing I didn't like about Romulans in TNG is they gave them subtle forehead ridges, so they must have split from Vulcan a LONG time ago to have gone through some actual physical evolution. Evolution is pretty slow if not nonexistent in a modern technological society. I don't think it was every disclosed whether Romulans had any telepathic capabilities although there were hints of some sort of special connection possible between Romulan/Vulcan couplings ala The Enterprise Incident, and then Saavik was half-romulan, but her origin was never explained.
Chalk it up to a regional/ethnic characteristic like a epicanthic fold in humans.