I’m not claiming that electric transmission is more efficient always because it isn’t. But as you say it is close.

In a scenario where a train drives at a constant speed forever, attaching the engine to the wheels directly is a clear winner.

However, with varying torque requirements, an ICE can’t always operate at maximum efficiency. They are especially bad at starting from a standstill. You can get a good overview of the concept from this wiki article. https://en.m.wikipedia.org/wiki/Power_band