I think the phrase "even after being given a warning and ample time to heed it?" part is important. "Zero" warning orbs are what most of us complain about.
For myself, I still remember my first day when I was all enthusiastic about "Wow, I can fly!" and then 'Plonk' I'm swatted out of the sky like a fly with no idea what had happened. My immediate emotion was hurt feelings that I had been rejected, but I later came to realize that what had happened wasn't personal.
Seems to me that we should not complain about just the land owners (some of whom are so clueless that they don't even know that setting ban lines will keep out their friends and alts) but with the orb creators themselves. How about a rule that you can't sell a security orb without a notecard discussing 'neighborly' behavior and recommending setting the transport site to a local public area so that explorers don't have to retrace all their steps? Does anyone make a security orb that has two layers - an inner 'zero warning' zone, and an outer zone with more warning time?
Also, could newcomer orientation sites include some information on ban lines and such? Don't know if I would have come back to Second Life after that first bad experience if I wasn't such a stubborn idiot.