This may have already been said, as I have not gone back and read the whole thread. One of the pictures shows a crossbuck with a stop sign attached. It can well be argued that this is sufficient protection based on the road and traffic. Inherent in a stop sign is that the vehicle at the stop sign must be sure that the way is clear before they move. Some railroad companies are beginning to fight lawsuits from crossing accidents if everything satisfies legal requirements rather than settle for the sake of public relations. Here, BNSF would have a very good case to fight against any claim or suit.
As to grade separate everything everywhere, that is simply not practical. In many cases physically not practical and for situations such as this economically not practical. There is not an unlimited bucket of money out there. All state highway and other public roads agencies have a list of things they want to do but are not financially able to do. There is this thing called the benefit-cost ratio. The projects with the highest benefit to cost ratio are, rightly, the first ones to get built. If the ratio is less than one, it should not be built. Usually, the ones that get built have ratios well above one. Unfortunately, this factor can be trumped by politics so that some politician's pet project gets built even when it makes no economic sense.