TrolleyImmobiliser

How much would such a service cost?

Induction loop buried in the ground just beyond the red line. Magnetic thingies in the bulges on the wheels.

Plausible

Getting trolleys out

• Pick it up, hold it over your head, carry it a few metres beyond the red line and set it down again.
  
• Would wrapping the receiver in tinfoil, creating a (poor) Faraday cage, be enough to stop the immobiliser from triggering? --Jumlian
  

Causing a ruckus in other ways

• Grab the whole line of parked trolleys and run the whole thing across it.  --Vitenka
  

Stuff wot's gonna get you instantly arrested

• Power cut - although they may have backup generators.
  
• MiltonKeynes solution - rip up the bollards that house the electronics powering the induction loop, thus rendering the system useless, and also incredibly difficult to fix without digging up the road again. --Jumlian
  

Just to make it clear, it wasn't Jumlian that did this.  It was just found ripped out of the ground on a Saturday, leading to the conclusion that it was "Friday night revellers" who incapacitated said device.  Whether it was intentional or not, it certainly stopped the immobiliser from working, and also I don't believe the miscreants were caught. --Jumlian

Why am I left with the feeling that ToothyWikizens are planning a surgical strike on Asda in order to remove... a trolley. --K

The ToothyWiki is bored.  It demands sacrifice.  You must bring it... a SuperMarketTrolley!  --Vitenka  (All this technology to lock the wheels, but they still can't invent wheels that don't lock, or ones that don't spin madly and try to turn you in the wrong direction)

ItsNotABugItsAFeature! --Kazuhiko