Because living a bat feces infested house is healthy. Also vampire bats.
For the most part there's no serious health risk, since they live in attics and garage rooves.
They're also small and they don't live in massive families when in houses, since houses don't tend to be large enough to provide for a big population.
And it doesn't matter if it's bad for your health. You can move away. The animals are endangered and protected for a reason. It's not ethical to kill them or diminish their population just because they're in your attiv and you can sometimes hear them at night.
Also, considering vampire bats come from South America, not many people living in England are going to end up sharing a house with one.
All the bats in the UK are fruit eating or are insectivorous.