So you have no choice but to take the risk. Fine. But that doesn't make it a "valid surprise".
In ideal world it wouldn't matter: we'd have time to properly analyse everything we use and clients wouldn't mind paying to having things done properly. We don't live in an ideal world so someone somewhere needs to decide if the risk is worth taking. If you don't push that decision on to the client (because your competitors don't and you fear it will reduce your edge too much) then you have to make the choice and take responsibility for it.
In ideal world it wouldn't matter: we'd have time to properly analyse everything we use and clients wouldn't mind paying to having things done properly. We don't live in an ideal world so someone somewhere needs to decide if the risk is worth taking. If you don't push that decision on to the client (because your competitors don't and you fear it will reduce your edge too much) then you have to make the choice and take responsibility for it.