[danhor]

Mont (if not allmost all) S-Bahn trains in Germany only have one staff member. The space for wheelchairs is directly behind the drivers cabin and the few times I've seen a ramp being deployed, it took the driver 1-2 minutes (Usually the automatically deployed gap filler is good enough). A large portion (I'd guess somewhere around 20-40%) of regional trains are also only staffed with the driver. The others do have an additional staff member, but they're almost always not safety relevant and only perform ticket checks, answer questions and help with ramp deployment.

The only times I've seen more than the driver on trams/Stadtbahns/metros, they checked tickets. This also happens surprisingly rarely.