It's very natural to lose patience with relatives or friends who seem hell-bent on self-destruction. It's profoundly irrational, and it exposes our own powerlessness and reminds us of our own weakness. Maybe this is something we don't like to think about. Maybe it's something we fear.
Addicts lie, steal, manipulate, and blame others. I have a couple of relatives who have been there - one in recovery and one still bumping along on the bottom. I've seen and heard the lies and the evasions, the self-pity and self-justification, and the refusal to take full responsibility for the carnage they left and continue to leave in their wake. The zeal of the converted when in recovery is painful to witness too. So much swinging of the pendulum, so little balance...
I live in the US and I don't think the UK is too far behind the US in perception and understanding of addiction, or maybe a better way to put it is I don't think the US is that far ahead of the curve in this area. Access to mental health services is not great in either healthcare system, but drugs both legal and illegal are freely available. Once those suckers get a hold, getting clean isn't always a matter of choice.
Rehab isn't guaranteed to have an effect because of a raft of factors working on an individual basis. It's not a one size fits all solution to the complex issues at play with each addict. Twelve Step programs can be all some individuals require, but they're not going to help everyone. People are very complex, and the factors that turn them into addicts or into recovering addicts are present in different combinations in each one. The interplay of biology and genetics and environment is one we can't always predict or control.
It's certainly fine to express exasperation at the behaviour of an addict and to protect yourself or your children from the harm they frequently do. It's the responsible response imo. But it's not an area where a non addict can claim any moral superiority or superior common sense or intelligence or ability to keep your feet on the ground.
Addiction doesn't choose its victims purely from the privileged, and privilege is no match for addiction when the addict tries to get sober. The idea that it should be easier for someone to recover if they have financial resources to throw at it or more to live for doesn't hold water, nor does the implication that the privileged addict has chosen self-indulgence over a meaningful life whereas the poor one has perhaps more of an excuse.
At a basic level, the opposite of addiction is not sobriety, it's connection, connection to the reality of yourself and your life, and connection to your family and wider society. It's a profoundly isolating and isolated experience, a malaise with a spiritual dimension (not in a religious sense) as well as biological and psychological. Judging does nothing for the addict trying to re-establish connection or wondering if seeking connection is worth it. Fine to vent though.