Recall in the 1960s that BOAC pilots had a "restriction of cooperation" - a/c not accepted for service with any defects at all (even if ok in MEL), no discretion to FTL, full instrument approach everywhere (ie no visuals), etc.
ok they did eventually go on strike (I think the first pilot's strike ever) but their actions in "working to rule" certainly had an effect!
BOAC Pilots Strike