Bring back the stocks
Obviously would never happen and more for a joke but I would genuinely love to see the public stocks come back for petty crimes such as phone theft, shoplifting.
Middle of Trafalgar Square (Or any public square) - Monday to Friday of criminals in public stocks just being pelted with rotten fruit and veg whilst all being live-streamed on social media (suspects will become recognised a lot more)
Someone can set up some stands to sell rotten fruit/veg to tourists and make it an attraction.
Would like to think the public humiliation would deter criminals more.