But I consider this to be the sort of central social idea that could be a vote winner for labour or lib dems just to offer something completely different. Imagine apprentices currently getting 150 a week while training for three or 4 years and then getting a 12 k ui to underpin it. They would pay just 20% tax on 7600 and nothing on ui of 12k so total income approaching 19'6 k they would see 1800 a month.
It is a good idea, clear plan of what to do and where we would get the money from. As Johnny has said above though it would lead to inflation. Not just unscrupulous businesses, but all businesses will raise prices. I think DW said yesterday that JSA amounts to around £3600 a year (apologies if that's incorrect), if we drive that up by almost 3 times as much, businesses will naturally put their prices up to reflect it.
I'm trying to put together an idea I had that is similar to UI, but more focussed on government paying for (or contributing toward) everyone's rent/mortgage, and utilities such as gas, electric and water and then giving them a very basic, modest UI to cover basic food costs. This way we could ensure that people have a roof over their head, warmth, running water and food on the table. I think giving everyone £12k to do as they please with could cause issues of what do we do when people waste it, blow it all etc...