Problem is it doesn't quite work like that. The third "strike" can be completely inane, and a situation where someone not on their "final warning" wouldn't be arrested for. It's a situation that is taken advantage of way too often by police and law enforcement in the US and not something I would want implemented in the UK.
We do not have to follow the USA's example.
They always seem to spoil an otherwise good idea by overcooking it.
Doesn't mean the principle isn't sound.
Any system of law that allows somebody with over 100 convictions to still be at liberty is clearly broken.
The only people who benefit are the legal industry. I bet they just love incorrigibles. they are the legal industries bread and butter!
(100 Police investigations (All that lovely overtime), 100 trials (With Lawyers on all sides being paid out of the public purse) and so on)
And do not forget the social and economic costs of the victims (Of course, not all drug related offences will have identifiable victims, but many will)
The costs associated with keeping somebody locked up for ever are likely to be far less over time.