Hmm, well I've been flying for 6 years and never seen a crew member unsecured for t/o or landing so you must be a very lucky guy
However as it is our job to make sure all the pax are strapped in, I've never seen that either
As for the engines powering up, I'm guessing you're referring to when doing so for takeoff. Again, unless it's safety related, I've never seen this happen however the amount of people making a huge fuss when on secure goes well into treble figures but unfortunately a large number are businessmen who do seem to think that the regs are more of an inconvenience to them instead of a safety mechanism for them and everyone else. Of course not all businessmen are like this as I am sure you are not F3G but unfortunately there are a lot that don't follow your example