Desire lines are where authorities intend for people to go one way, but people (especially pedestrians) quite logically ignore them and go a different way.
Often they indicate poor design.
Here are some quick examples from my neck of the woods.
Down at Southland, the new station is a roaring success… except for the pathway to the shopping centre, which diverts people via an indirect route – though at least it’s got priority zebra crossings all the way – visible at the left. Still, an awful lot of people come out of the station and instead dodge around the fence and make straight across the car park for the entrance. Are we really that surprised? Hopefully sooner rather than later, Westfield will fix it.
The centre of central Bentleigh: the station. This new pedestrian crossing is very welcome, as it connects the westbound bus stop with the trains. Amazingly, before the grade separation, there was no nearby crossing. With a little thought, they could have made this new crossing wider, stretching towards the bus stop, as when buses arrive, there’s a swarm of people crossing the road.
And this, around the corner. Having a zebra crossing is good, but it’s clearly in the wrong place. It should be no surprise at all that most people cross at the point aligned with the supermarket entrance. Authorities must have realised this, or there wouldn’t be this signage.
Often this type of thing appears to be just trying to make life difficult for pedestrians.
I really hope whoever is responsible for these designs is observing how people use these spaces, and isn’t continuing to make these mistakes.