As you can infer from the picture below, the groundkeepers at UC Riverside don't like it when we walk on the grass:
Let's start with the math.
One concrete edge of the site pictured above is (I just measured it) 38 paces; the other edge is 30 paces. Pythagoras tells me that the hypotenuse must be 48 paces -- 20 fewer paces through the grass than on the concrete. At a half-second per pace, the grass walker ought to defeat the concrete walker by 10 seconds.
This particular corner is highly traveled (despite its empty off-hours summer appearance above), standing as it does along the most efficient path from the main student parking lot to the center of campus. There are 21,000 students at UCR. Assuming that on any given weekday 1/10 of them could save time getting to and from their cars by cutting across this grass, and multiplying by 200 weekdays, we can estimate the annual cost of forbidding travel along this hypotenuse at 8,400,000 seconds' worth of walking -- the equivalent of 16 years. Summing similar situations across the whole campus, I find lifetimes' worth of needless footsteps.
The main reason for blocking the hypotenuse is presumably aesthetic. I submit that UCR is acting unreasonably to demand, every year, 16 years' worth of additional walking from its students to prevent the appearance of a footpath along this hypotenuse. Footpaths through grass are simply not that much of an eyesore.
But even granting that unpaved footpaths are a terrible eyesore, the problem could be easily remedied! Suppose it costs $10,000 a year to build and maintain an aesthetically pleasing concrete footpath along the hypotenuse -- at least as pleasing as plain grass (perhaps including even an additional tree or flowers if necessary for aesthetic equivalence). To demand 16 years' needless walking from students to save the campus $10,000 is to value students' time at the unconscionable rate of seven cents an hour.
These calculations don't even take into account UCR's costs of enforcement: The yellow rope itself is an aesthetic crime worse than the footpath it prevents!
In light of UCR's egregious moral and aesthetic choices vis-a-vis footpaths, I am therefore entirely in the right to stride across the grass whenever I see fit. Raise the pitchforks. Fight the power.
But I can't seem to do it while looking a groundskeeper in the eye.