My opinion? I think Luke simply generates a better signal. Either the antenna is higher, more gain, and/or they push more power out. I can receive Luke's ATIS at 7th St and Bell (my house), Cactus and Tatum (GF's old condo), and now at 40th St and Deer Valley (GF's new condo) pretty darn good. All this with a ham HT or Grundig 750. I can't even pick up Scottsdale's ATIS at 40th St and Deer Valley and this is on the second story. She just isn't that far from KSDL to not hear the ATIS.
I think it's just because the base is military and not civilian. One weekend KLUF had a special operation going on, thus they were directing KDVT traffic and others on the west side of town. You would think KLUF was a mile away that weekend. The controller/signal was so strong.