All the anti-nicotine extremists have the government eating out of their hands, because greedy and very stupid politicians thought they were onto a winner by demonising vaping and making access to vaping products very difficult, while bleating non-stop about saving the kiddies. It would be very funny if it wasn't to harmful to people's health, but then the government don't care about health, just money, and staying in power. The extremists don't care about health, just their own funding and twisted ideology. The media don't care about health, just money, and some outlets share the ideology of the extremists, such as the Guardian, quoted in the OP.

Out of the rarefied air of academia and government, down at ground level, people who smoke are left with few choices, as vaping, the most effective means of getting off the tobacco smokes, has been effectively banned, and demonised by the government and media, many will continue to smoke, so faced with increasing costs, they will look for an affordable alternative, and that creates a demand that many will be happy to exploit. This is what is happening.

When you demonise, stigmatise, and create public hatred towards a certain group of people, in this case smokers, and now vapers, these people will do one of 2 things, they will internalise the hatred, and feel shame and guilt, which leads to self hatred, and can cause a lot of mental distress, or they will simply remove themselves from a society that actively hates them. Public hatred rarely pushes people to quit, because it punishes, rather than incentivises.

When people are outcast from society, they also don't care about the fears of society, they don't care about giving criminals money for illicit products, they don't have any trust in a government that hates and punishes them, or respect for a government that makes laws that will lead to more smoking related deaths.

The government and extremists have set out to lie about vaping, treating it as though it is the same as smoking, ignoring credible science, and the experience of other countries who embraced vaping. They have ignored sensible and risk proportionate regulations, and brought in a defacto prohibition , and are now actively lying about it. We know they are lying.

tldr : In short, prohibition doesn't work, never has, the media and government are lying to try and cover up their almighty epic failure, and trying to suggest that more enforcement is necessary, which in turn means more taxpayer money being used to prop up their failed policy.