Why? EVERY temporary work visa I have ever had has had a declaration section where I acknowledge that its temporary and in no way entitles me to residence. Its not a hidden suprise.
Acknowledging that it sucks doesn't mean it doesn't suck. It's unfortunate for anyone to have such an unstable residency, where they could have to uproot their life back to the other side of the world with very little notice, on top of being laid off.
In USA, H1B visa is a dual intent visa and implies a possible path to permanent residence and citizenship. This was shared with me by the immigration officer back in my country of origin (he was not interested in my ties to my country of origin and explained this when I asked why).