I find it quirky that people are complaining that they can only break the official legal speed limit by 5 kilometers...so what is it? you want to break the law by more?
The official speed limit is 100kph and they are allowing you 105....gee whats your problem?
The problem is speed limits in many U.S. states are higher than 105 kph (65 mph) and it does not sit well to limit the truck under the laws of two provinces that we rarely enter.
Diane and I drive slower than many drivers to conserve fuel. Our customary open-road cruising speed is 55-60 mph. But there are times when faster speeds are desirable. Here is a recent example:
On a run from Washington state to New York, the route took us through Minneapolis, Minnesota. That is our home express center and Diane's dentist is there. Due to have her braces adjusted, she called ahead to see if she could get an appointment. If that could happen, it would save us going out of service for two days and flying her home from wherever we happened to be a few days later.
The dentist was unsure when we called a day ahead of time. The next morning, and as we just crossed the North Dakota/Minnesota line, we called again and the dentist said he could get her in if we arrived at a certain time. We could, but only if we ran at the posted speed limit (70 mph) from the border to the the Twin Cities area where the speed limit declined to 60 and 55 mph.
The extra money we spent on fuel driving 70 mph more than offset the money we would have lost to go out of service for two days and paid to fly Diane home and back. Had the truck been speed limited, we would not have been able to use the posted speed limit to our significant financial advantage.
Such circumstances do not happen often, but they do happen. So, to answer your question, limiting the top speed of the truck is a problem that manifests itself in ways that cannot be predicted or always quantified but remains a problem nevertheless.
Another example comes to mind. Again, this is not something that happens often but it does happen. Driving at speeds above 65 mph got us to a delivery before the shipper closed when driving slower would not have. The difference is getting freight off the truck sooner, which builds dwell time earlier, puts you ahead of other trucks and gets you dispatched on the next load quicker.
Non-financial issues also come to mind. As I write this, we are deadheading home to pick up a load. It happens that the shipper is very close to home. The deadhead is a full day drive. It is not happening now, but it could. In slightly different circumstances, if family or friends were gathering for a Friday night dinner or event, we might be able to join them it if we drove at the posted speed limit. We would not in a speed-limited truck.
It is easy to imagine a number of scenarios where speed may be desired or essential to get to a desired or family emergency event at home.
Short story: It plain sucks to buy and operate a truck and then limit it to speeds below the posted speed limit, even if you normally cruise well below the posted speeds.