Freight trains are much heavier on the same gauge. The weight limit for a BART train loaded is 55 tons. Compare that to a freight car which weighs 30 tons empty, but can carry up to 100 tons worth of stuff inside it.

OK, but I assume those trains are sometimes moved around empty?

Ideally no. But a lot of them are also flat beds and cattle cars that’ll let air through them when totally empty.

I’m assuming that wind is taken in as a factor when deciding what stock to send where though.

You do hear of derailments due to wind sometimes for empty freight cars.

https://en.wikipedia.org/wiki/List_of_wind-related_railway_a...

Interesting stuff!