Practical miles is a clever term to use because it all depends on whose definition of "practical" they're referring to.
Usually they use PC Miler and just type in the names of the departure & arrival cities. They won't go from the actual addresses because it takes them too much time when they're getting the miles for lots of trips when they're processing payroll. It doesn't have to be PC miler, but it's modern software that's more realistic than the old HouseHold movers Guide (HHG) which gives the short miles, from city limits to city limits. Companies that use HHG mileage are stealing from their drivers every day & some have been successfully sued over it before.
When I drove for Covenant Transport in 2004 I was given the mileage with the load info on the Qualcomm. When I compared it to the software on my computer, and even programmed the actual route that came over the Qualcomm that they wanted me to follow, it was always a LOT longer. I'd say I was ripped off about 50 miles a day, on average. One one trip, which was an empty run from some Denver suburb, to some little town in southwest Kansas, I drove the exact number of miles the Qualcomm said it was, following the routing they gave me, and I was about 40-50 miles short of the destination. I sent a QC message to dispatch saying I can't find the shipper. A few minutes later I got a message saying that the QC was showing me being about 40 miles from the shipper. I replied "Load info says it's XX number of miles, I've driven that many miles, why am I not there yet? There's a huge difference between the mileage I've been given and the actual distance" The only reply was "Call Rand McNally".
I quit about a week later.