Blacktop is black because its primary ingredient is bitumen (asphalt), which is… black. I suppose it could be made with coloring agents, but it would take a lot of coloring agent to overcome that black base material, and paint would wear off too soon (and thereby create its own environmental ill effects). All of that would make it pretty expensive, which large users of asphalt are not so keen on paying.
But that’s not “heating the Earth” directly, as it simply reduces albedo, which is a measure of the planet’s reflectiveness. In this case, the Sun still heats the Earth, but reduced albedo helps to hold that heat instead of reflecting it back into space.
Of course, we could fill all of the roads and parking lots with white-roofed (or mirror-roofed) cars. That would help to offset the reduced albedo of the pavement…