Valid points from my view. I am thinking the plugs I installed can go 100k. I see having consistent quality across the board as a Hyundai issue. My first week of ownership my brake booster was recalled. If I ever get a different car I would go with Toyota since they are more consistent with quality.I offer you this:
To me those plugs look a bit "dirty" but okay.
The threads show signs of seepage, as you mentioned they were under-torqued in the other forum.
I wonder if the Owners Manual has a shorter plug change interval because H/K knows the Yura plugs
can't be trusted for as long as (100K miles) iridium plugs from Denso, NGK, etc.