According to wikipedia "thermoplastic road markings" are thick, and embedded with glass beads.
The binder resin is heated to 400〫F in the machine pictured below, and layed down in two 30mill thick ribbons, creating a depth of 60mills, about twice as thick as your credit card.
The lines need thickness to hold the glass beads, and the optics are actually improved as the covering paint wears away.
But lines like this last only a couple years in an urban environment, and need to be reapplied every 24-30 months.
After years of illegal U-turns, Lincoln Avenue is finally earning its stripes.
But remember that Lincoln Avenue pot hole?
They are not actually fixing it just yet.
They painted around it.