If you've ever seen the traffic in Pnom Penh, Cambodja, you might reconsider.
In truth, traffic lights aren't necessarily bad. I am certain they can be useful in certain situations. But rather than allow states to own roads, a situation that allows costs to be socialized and encourages blanket solutions (sometimes, to nonexistent problems), the roads should be privately owned.
Owners can operate their roads in any way they see fit. Some might install traffic lights while others may choose not to, depending on terrain, desired traffic flow, presence of businesses, schools (private, of course), etc. Owners can charge fees to use their roads, so that only those who use them pay for their usage. In such a situation, owners might be compelled to prioritize and market certain features, such as their roads' efficiency, the availability of more/better restaurants, or more/better sidewalk hookers.
And perhaps, as Walter Block argues
here,* the roads might become a lot safer.
* Good book.