There’s loads of standard gauge steam in the UK with regular service, but it seems that these are excluded because

1) flying Scotsman as it’s not regular service with integrated tickets but runs on public railways and stations

2) festiniog has integrated tickets and runs to normal station but is narrow guage

3) north yorks, swanage, bluebell, svr, Dartmouth etc are regular service to real stations but arent integrated. Dartmouth (kingswear) is certainly used for non tourist purposes.