Well no, it's not a matter of size nationally. It's a matter of the size of the business or business activity within that state giving rise to an economic "nexus" with that state.
Transit through a state is not considered a business or a business activity, hence the trucking company could not be regulated. It could be different for a travel company, but in such case that would be services income which is not subject to a sales tax.
If a company is paid to transit something, and it pays a trucker to drive though a state then clearly that's a business activity. It's complected, but for a example is states can only regulate the emissions of vehicles registered in their state. As a counter exmaple states can regulate weight limits for trucks.
It helps to look at it this way: is the actual business activity of getting goods from point A to point B related to the state for any economic or business purpose other than incidentally transiting through the state? (For example, are goods being delivered to customers in that state?) If so, you may but probably do not have a business activity in the state.
With a travel company, the distinction is that the journey is as much a part of the business activity as reaching the destination.
Transit through a state is not considered a business or a business activity, hence the trucking company could not be regulated. It could be different for a travel company, but in such case that would be services income which is not subject to a sales tax.