Originally Posted by RaulRo

You can not get HON tag on UA or any other carrier outside of LHG (and your luggage will not be as HON luggage later on LH system).
But if you ask it on the airport, where you connect to LH, they can assign HON to your bags in their system. If there is enough time, they can also retag your luggage.
Happened to me in ORD before and in BKK just 2 weeks ago. But that is better to ask and not just wait that it will be offered proactively.

HON tags in my case have ususally very good help. After "years-long training" (actually several complains and reminders, that this is something for what LH/LX are paying for) at my home airport the HON bags are on 99% cases first on belt.
Actually the visible recognation is absolutely nothing somebody should be shamed. I do enjoy to be escorted to front of any line and to be boarded before even official boarding starts in good airports.

About the HON tag technical aspects AFAIK it is depending on aircraft. For the long-haul planes and LH A321/320, where the luggage is in containers, HON bags are separated form other bags at all and for that, if the system is fully computerized, is needed that luggage tag number in the system have HON priority. So it will be also offloaded seprate and first.
If the plane is small, then the visible HON tag plays crucial role to show to luggage-workers, that this bag must be first on belt. Of course, unfortunately there are many "proletariat"-kind workers who try to show their disrespect to important pax and try to ignore it, but in many airports it works.And if it do not work out, complain, comlian and complain. And on most cases finally it will start to work out.
Same as Group 1 boarding on beginning of flight. If that was not honored I ALWAYS asked the gate agent, why he/she is not following rules and made complaint to airline. Currently the situation is much better with Group1 boaring.