Rear wheel removal - something odd, or is it just me?  By  wyopaniolo210 (Read 976 times)

I'd go to Harbor Freight and get an impact wrench for that before scratching your head too hard.

Looks like a variation of the 'NY-lock nut' to me. It's a special 'lock-nut' with a (generally) Teflon ring inserted to prevent vibratory loosening. Note the threads of the bolt 'cutting through' and pushing up the insert material at the 9 o'clock position in your photo:


...and compare with an unused nut:


While the insert will add a bit of resistance during tightening/loosening, it shouldn't rise to the level of difficulty you describe. As mentioned by others I'd wager it's simply a matter of exposure to the elements resulting in corrosion lock. There is nothing 'special' about these nuts that would lend themselves
to any greater tendency to 'break things' when attempting to remove
them. Typical removal procedures should suffice. Either a torque wrench, breaker bar, or heat applied to the nut. (Note that heat applied will 'ruin' the insert, but a replacement nut should be easy enough to find.)