Big Tobacco/Big Pharma is playing both sides of the game. They win either way. They literally have lobbyist pushing pro/anti vape legislation everywhere.
If vaping gets heavily regulated, they have the money to swoop in and corner the market. then it just becomes smoking 2.0 and they control the means of production and distribution. They can afford the time and legal effort to push PMTA.
They are also purchasing very quietly flavor manufacturers, e-liquid manufacturers, distribution channels, and so forth. If vaping manages to survive regulations, they get to control the means of production and distribution.
By putting hurt on the industry now and staying quiet they can cause small vaping businesses to starve out, allowing BT and BP to swoop in and get them cheap and just absorb them into their massive umbrella.
The FDA and whatever the UK equivalent is doesn't care about vaping in the slightest. They care about money. In the US, states stand to lose a lot of tax revenue they are banking on when smoking rates decline, Big Tobacco loses when they do not get to sell cigarettes and Big Pharma loses when people are not sick and dying from smoking or buying their smoking cessation poisons.
Vaping has disrupted all of these industries and they are pouring lobby money all over to either destroy or gobble up the 11 billion dollar vape industry.