has errors and Omissions insurance
which covers them from liability in the event they are sued for "missing things".
Don;t believe anyone who tells you a surveyor
has no liability regardless of what they unilaterally write in the survey
document. These guys wouldn't pay for E&O insurance
if they were free of liability.
I would encourage you and anyone else who has a bad survey
done to sue the guy who did it. I generally don't suggest litigation as a first choice in any circumstance but it's way past the time these guys understand they can't get away with shoddy work or negligence.
All buyers should make it a point of asking if the surveyor has E&O coverage. Asking isn't necessary as virtually all of them do but it sends a clear message you want a thorough survey and that they have liability for failure to meet a reasonable standard of care without which you may seek damages from them