I think they should have to do community service. Cleaning up the block surrounding Apple Stores in front of every Apple Store in London for the next year and paying back the cost for each phone seems appropriate.Credit to the kid for apologising and taking full responsibility. I think 310 quid each and a lifetime ban from that Apple Store would be a good punishment. I think it would be harsh to give them criminal records as this does appear to be a silly ill thought out mistake. They should pay for what they did of course, I just hope this turns out to be a valuable life lesson.
----------
You need to live in the US to fully understand the justice system here in the US and how it works. There is nothing like living in it to fully understand how things work here in the US. You can site all of the studies you want to about jail effectiveness but that doesn't explain how our system works. Every justice system has its own benefits and drawbacks that people can find if they look for it. Also one could argue that much of the drawbacks in the US system are related to how they treat drug offenders etc...I rest my case. There is nothing more to say to you.
You believe in your justice system. Which is broken and flawed. (Again evidence everywhere)
You believe in jail time to prevent crime. Which is proven time and time again to be ineffective.
You believe that I have to live in the US to understand your justice system or make an assessment of your society.