The only thing to remember is that (in Canada, and I assume the USA) commuting to work is something everyone does. Travelling from your “normal place of work” to a jobsite or customer is part of the job. Commuting therefore is not a business expense for you or your employer, unless it is so extreme as to need reimbursement.
If I work for ABC, and am on contract to XYZ, so I go from home to XYZ every day, that’s commuting. If I go to ABC in the morning, then go on to XYZ one or more times that day, that’s work travel. If I fly to XYZ every Monday, stay in a hotel, and fly home Friday - that’s business travel. As others mentioned, the exact details have been settled in umpteen different cases over the years.
When I worked in a small town, we used to joke about how valuable we were to our wives dead, if the plane crashed while we travelled to the head office. It counted as business travel for a worker’s compensation pension; the life insurance had an accidental death clause which IIRC paid double. Plus, there was an additional amount of automatic life insurance from the credit card from using it to pay for the flight.
We had one fellow who was cycling to work once; he was heading downhill full speed with his head down, and did not realize (pretty dumb) until he hit it that the work crew had dug up the road at the rail crossing and the rail was a four-inch high obstacle in his way. The company tried to deny his workers comp claim, but the crossing was inside the company property line and the union pointed out that the company has supported the WC claim of a non-union employee injured in a car crash on that same road, also heading to work.
The point being, as soon as you cross onto company property on the way to work, you are covered. Some people suggest that even before that, on the way to work, you are covered. I heard of one fellow working for a small company who had a battery blow up in his face when he tried to jump-start his car. Since his job included picking up the rest of the crew to take them with him to work, he was considered “on the job” trying to start his vehicle because he was reimbursed for gas costs for this task. Workers’ Comp paid his lost salary and costs.
In fact, I once drove the several hours to the next big city for a meeting, so I would have my car there for the weekend. The head accountant refused to pay just gas, insisted that I put in a mileage claim (IIRC about 40 cents a mile then, to a maximum of equivalent airfare). His logic was simple - you or your boss cannot pick and choose reimbursement, or else we’ll end up with a scenario where “Fred can go to the meeting if he drives and we pay gas, but Joe we will fly there.” The rule was everyone is treated equal. Actually a nice guy for an accountant, and a good company policy.