I'd say thieves actually go for the cheaper lock and I have some extremely limited evidence to back it up. My friend bought a very cheap POS MTB at Target. He also bought a cheap cable lock. I pointed this out to him and he brushed me off then a few weeks later someone stole his bike. So he went back to Target bought the same exact bike but he went out and bought a Kryptonite U-lock and reinforced cable set. He still has the bike. Also I bought a Kryponite Evolution Series 4 U-lock and Master chain lock when I bought my first bike three years ago and I still have my bike. Why would a thief fiddle with a harder lock when he can clip a cable and scamper?