Why are the streets and roads always wet in movies?

for the reflection, also it's easier to do stunts on a slick road

edit... maybe for the visual effect. it's more appealing to the eyes. for a night scene you will see lights reflecting. for the day i guess it looks "cleaner" (darker)?

actuality is there are various advantages to wetting the pavement down in the previous filming. the biggest reason is to maintain the pavement from "blowing out". Dry pavement looks impressive and overexposed on action picture/video whilst the publicity is desperate for actors and automobiles. moist pavement seems dark, the way our brains think of it might seem.

The tread on a tire are built to stick to the concrete/asfault. If you were to try to slide your car on dry pavement, the odds that you'll flip into barrel rolls are higher then when the ground is wet.

many movies are shot in vancouver canada because of tax breaks and better union co-operation, it rains 312 days a year there like it does in seattle, tires do not "squeal" on wet pavement so if you hear tire noise on wet or dirt road it has been dubbed in later

Orphan tears.