<<My overall beef is we were charged while many others were not.>> sorry, have to say welcome to how the world, and the airlines, works. It's always the same on many airlines of them having specific limits and us exceeding those limits and sometimes getting caught and having to pay. I've been on Air Pacific multiple times and they enforce weight limits if they catch you. Their not being diligent about every agent charging people is a benefit because then sometimes you pay and sometimes not. I always wear a backpack and though I try to reduce weight, always weighs a ton because the essentials are in there. You wear it up to the counter like it's a simple backpack though its weight is cutting your arms off. Sometimes you make it, sometimes you don't. I think you got jerked around more than usual but the basic process is the same. Actually multiple places I know of won't let you take it on the plane even if you are willing to pay an overweight fee. We've also planned for paying for an extra bag when coming back, rather than angsting over making the 50 lb limit. On Singapore Air from Bali to SFO, it was a flat fee of $330 for ANY overweight bag regardless of overage, but $130 to add a third bag. We just paid for the third bag and had plenty of room to bring it back. Just another drop in the trip bucket.
I'd suggest that it's also likely unrealistic to expect much different behavior as regards "having their act together". This is where they invented "Fiji Time" and are always sure to inject some. We learned Senga ni lenga ("no worries") from them.