I think it was because of two reasons. First, the sort of people who go on Erasmus and Interrail tend to be the sort of people who could have afforded it anyway - it is a subsidy for the well to do.
And secondly, far fewer people go from the UK to other countries, than come from other countries to come here, so it is a financial drain.
You could argue that it was a good idea for soft power reasons for the UK to do, but it doesn't seem to have built up a lot of European good will so far and perhaps the government has reasoned that the money is better spent elsewhere.
Only if you subscribe to the zero sum idea that there is a fixed pot of money which must be shared out between competing claims on it. Unfortunately our current and recent governments have propagated that notion for their own gain.
It neglects the fact that foreign students in the UK spend money in the UK economy thereby propping up jobs and economic activity. When my daughter did a year studying abroad in Germany the funding she got was nowhere near enough to cover her rent and other costs. So something like 10 grand of British money ended up getting spent in the German economy to keep her going.
Absolutely not in my experience. They don't tend to be super poor, they are college demographics. But among social classes that do go to college, it actually enables people who could not pay for it. These programs are a way how students for whome it would be expensive go abroad for few months.
The missing tuition support is really harsh, especially if Turing is for the US
I don't see this working in all honesty.
The UK withdrew from the Erasmus scheme as part of Brexit seemingly for no other reason than to discourage cultural integration.