There is no remote control for the train crew. They get out and operate a lever, at least that's what I've seen. Usually, they'll call the dispatcher to have the track switched.
The use of the automatic switches is based on the railroad, place, kind of service, etc. If it's a busy mainline with a big dispatching operation, there are remote switches. If it's a siding that sees a boxcar every two Thursdays a quarter, then a manual switch will suffice, although that could be an automatic switch.
An old branch line or industrial spurs have manual switches, or sometimes automatics. This happens because sometimes what is now a branch line was once a busier mainline and the RR didn't want to bother to replace the machines. Other times, the route was always manually switched and that's how it is.
Sometimes, the automatic switches are pulled and are replaced with manual switches. This occurred in East Deerfield, Mass at the big former B&M yard. This once large yard was stripped down under Guilford and most of the automatic switches were removed and replaced with manual ones. The only automatic switch left is at the throat of the yard.