I'm not sure how it is today , but 10 yrs ago I attended a regional town hall meeting in KC ;that Sears Service was doing. I remember Sears techs comparing notes. The techs in St Louis said in certain neighborhoods they always sent two guys.
In our metro (10 yrs ago, not sure now, I've changed jobs) our tech said it wasn't an issue even in the questionable areas. He was the emerg furnace/water heater tech and often got called out at night. He said he went alone and never had a problem...but 10 yrs ago St Louis was a tad unsafe //
So perhaps it is still a concern if you live in the inner city of St Louis proper.