Personally I think it's a combination of
Lax social responsibility (fed up of the, addicts are victims and clearly have no autonomy rubbish) now you can emphasise and try to help but people need to stop bloody acting as if them shooting up heroin couldn't be helped. There's too much sympathy and allowance for drug culture behaviour. When i was 15 I wouldn't have known what half the street drugs were or where too find them. Now shooting up or popping pills is seen as normal, and at younger ages. It's seen firstly as some sort of out of control illness rather than a lifestyle choice leading to illness and criminality that people willingly made. So why would you not do it if your life is a bit shit? You're a tragic figure people have to feel sorry for. How exciting.
Oh and people will go nuts on me but there's plenty of addicts that do not meet a rehab bed criteria because they are feckless and will just not truly want help in that time or make any rehab effort.... sorry. Truth is uncomfortable. CMHT try to prepare them for it but that suggestion is right around the time they decide to well and truly disengage...
Higher alcohol costs, though that also didn't reduce the amount of alcoholics so meh.
Cheaper drugs, seriously. Ridiculously cheap and most people get started on even cheaper legal medication abuse. Don't know why they are cheaper up here but they are- mind you next cheapest has been from cumbria-yorkshire county lines route (cmht worker we've dealt with county lines people before) so that geography may have something to do with it
Poorer and also less educated areas. Mums family and me from a rough estate but my mums family emphasised work + learning... yet it's obvious (as in even locals not mh professionals casually talk about it) there's mums from school gates who take cocodomol (when they don't need it) to get high... yeah really. And those that see any form of education beyond basics as 'snobby'. The kids all have fantastic potential. But few if any will achieve it due to the culture they are growing up in. It's also very tribal like, even the idea of moving town or commuting for a job is laughable tbh.
So yeah. Combination but after working in CMHT I truly believe the casual attitude towards it all and public glamour/misplaced sympathy has made this worse.