The purpose of qualified immunity is to permit officials to carry out their discretionary duties without fear of personal liability or harassing litigation. It applies to all parts of government. Didn't get the building permit for your kids horse barn? Sue the planning commission members individually. Animal control writes you a citation for Puddles not being on a leash? Unleash the lawyers. Health department gave yo…
Other countries don't have a problem with officials getting sued. In the UK there doesn't even seem to be a problem with employees getting sued; cases always seem to end up being against the employer. So why does only the US need "qualified immunity"? (That's a real question, not a rhetorical one.)
(our own comparable issue is probably Northern Ireland, and the still-outstanding litigation around Bloody Sunday and "Soldier F" etc)