Nothing against tattoos, but the high street in some places does seem to be infested with them, like nail bars, turkish barbers and estate agents
Yes, you have to be careful. You do have to get a licence to tattoo, but you don't have to pass an exam or anything to become one. There are health & safety rules, regulations & certifications that have to be complied with but that's it - nothing to measure your skills as an artist.
In the old days a tattoo artist would learn their trade from another - an apprenticeship - and they'd work their way up to tattooing people. It was almost a kind of closed society. These days anyone can buy a tattoo gun & ink - you can buy a gun & kit off Amazon for around £50. So anyone can set up, so there are some really dodgy artists out there.