With the knife example above, it's obvious when you create a problem.
With the shovel problem you mention, it may not be so obvious you create a big problem. A cable is a cable, it's not necessarily obvious what will be the consequence of a bad shovel move cutting a cable. But it's rare, and easy to detect and locate.
With telecommunications, it's hard to realize you're creating a problem in the first place. And it's very hard to pin-point and solve. Hence the strict laws to prevent the issue in the first place.
As an example of how easy it is to be a problem without realizing it. There was an article in LWN (too lazy to track the ref...) about guys doing a free software 2G stack. They were quoted saying that they just did tests with the transmit power stuck at the maximum because it was easier (yes, AGC is tricky). And they were doing the tests on a live network.
Does this mean anything to you? Well, to a telecom engineer this is pure evil incarnate. You just don't mess with power, and don't create interference in neighboring cells and being a nuisance for all but yourself.
People expert in one field tend to consider themselves good in other fields, particularly if they're both technical. And when you're new to something, many times things seem simpler than they are just because you don't even realize the problems lurking behind the surface. One has to be very careful when dealing with telecommunications not to be bitten by this. It's a very complex domain, no person can cover it all actually.