Because they are stuck in the past. Because the pharma companies don't make shit loads of money from the taxpayer if you vape a little herb. I think pharma is the main issue and money. As the current and older generations of doctors retire and are replaced with later generations these attitudes will likely fade over time. There will probably be full legalisation of it within the next 25-50 years. But right now we are in that early stage where some people are on it, but the media still hypes up the evils and people are overly gullible and believe the hype. In 10-20 years, who knows.
It's gradually changing, but for me anyway, I'll tell my consultants if they ask. If someone doesn't like it, tough shit. I don't really care. They aren't taking it for an ailment so they can go do one. As they say, opinions are like assholes, everyone has one and in the
NHS a lot of people especially are them and have them. It also seems to be a bit more of a southern thing in the UK. When I mentioned it while down in Cornwall in hospital one night, I got some real shitty attitude from the doctor that was treating me and if I hadn't been trying not to die he would have got both barrels off me over why he thought his views trumped a top notch doctor that was a leader in his field. But up here in the (almost) North, they just don't care. One guy at one of my clinics, that does tests and takes blood, said to me "better that than heroin", which was a borderline crappy comment to make, but it's also true and it made me laugh. After all, opioids are the bane of modern society.
With regard to landlords and employers, you can wave the Equality and Disability Discrimination Act's in their face if needs be and from past experience before being on this, it's usually enough to pull them into line pretty quick. The police on the other hand are a law unto themselves. But even they seem to be getting a little better a late. But I still regard vaping herb as a covert activity. I'm not overt about it in any setting, well except if i'm sat in a place far away from people or walking/climbing out in the peaks. I also don't drive on it, within 6 hours of vaping. I have my own rules that i follow and I largely never have issue with people. If you choose to vape around people, conflict is inevitable at some point. But if you surround yourself with your people who are ok with it and understanding that can negate some of the issue.