No they are not street legal.
no.
Yes. ATVs (or "quads") are legal in Texas.
Because, I think atvs are not build for roads they are made for deserts.
Yes, you can.
Because they are not street legal.
nope cause they're more dangerous at high speeds than motorcycles.
Most ATVs are not, technically, street legal, so it doesn't matter how old they are. If it doesn't have a license plate, it's not legal for them to ride it on the street period.
Yes.
No one will, they are not street legal
Generally, ATVs are not street legal in Colorado. There are only certain counties and towns in the state that do allow off road quads to be ridden on city and county roads. ATVs can be ridden on US Forest Service roads and trails with the purchase of an annual pass from the Colorado State Parks Department. The annual fee for the pass is $25.25.
In my jurisdiction, ATVs are like tractors: They are legal to use offroad, but it is not legal to drive them on a public road without registration, except for crossing the road from one field to another.