Obviously, this part is under construction and that is why the lane markings look like that. They use a machine, which is a truck with automated paint spraying mechanism in the back and is used at regular intervals to remark the lanes. Also, the paint used is formulated specifically for that surface and weather conditions. In Phoenix metro area, they don't use pain at all. It is a sticky, reflective strip that gets bonded to the road surface when heat is applied. 
There is highway maintenance department, whose only job is to make sure all signage is not only clean but legible from a set distance. They are also responsible for keeping the median area maintained. Road signs have been thoroughly tested to withstand all weather conditions and most vehicle impacts. If a motorist happen to crash into a road sign, they have to pay the government to fix it.
The fonts on the sings have also been studied extensively for legibility. I remember not very long ago that a new font was developed for interstate signage which is even more readable than the current font. All signage in the US will be changed over time to use this new font eventually.
If you notice, there are no trees on the sides or in the medians of interstates. It is by design. Trees pose a serious hazard during bad weather.
I didn't intentionally make any attempt to avoid taking any photos. If you notice, I have no photos of any crash. It is not because I didn't take the photo, it is because I just didn't see any.
The worst thing I saw on the interstate was tyre tread that had come off of semi trucks. To remove those, highway petrol starts a break in traffic and the maintenance crew removes these. They are not allowed to just walk around on the interstate.
Most of the interstate system is absolutely free. There are some toll roads which can be avoided by using state highways in most cases. The tolls are not outrageously high, however, and depends on the vehicle and the distance traveled.
Tax payers have the ultimate say here. They speak by voting government officials in or out of the office. Generally speaking, most people are satisfied with the road network in the US. It is fully mapped by numerous different sources, obviously, and is very reliable. But sometimes tragic incidents happens, either due to someones negligence or by a natural event. Collapse of I-35 bridge in Minneapolis, MN is a good example. It was caused by human error. It was an old bridge and an independent inspection agency had already pointed out structural problems in that bridge. Unfortunately, the highway maintenance department responsible for paying attention to these findings ignored them and the result was a devastating and completely avoidable loss of human life. After this incident, all bridges of similar design across the US were shutdown immediately and inspected thoroughly to avoid any further incidents.
You asked about public transportation; I recall seeing only one Greyhound bus during our travel. Most people fly and some use trains for long distance travel. Others like to drive. Very few use buses.
