re:  "... i have seen something shoking in the states, no yield sign on
freeway entrance??????????????????????????"

In California, at least, I believe it's the law; ie, entering traffic has
the right-of-way.  A benefit is that it reduces the number of rear end
collisions on the ramp.  (Hope I don't have to explain why.)  But an
unfortunate result is that many people then refuse to drive in the right
lane to avoid having to adjust their speeds to accommodate merging traffic.

//Jack