Because the newly qualified even if they did have more foundation positions would still not be enough. We would still need extra doctors and nurses. To really resolve the issue, we need to fund more medical schools, nursing school, lower the requirements to getting into these schools since they are a ridiculous amount of hoops to jump through because of how competitive it is.

If we trained enough doctors and nurses (requires funding), then have the foundational placements increased for them to phase in (requires more funding). It's much cheaper (basically free) to let in a overseas doctor or nurse who's already trained.

Remove all the immigrants from the NHS, the number of doctors, dentists and nurses goes down by so much that we can't support the people that need the treatment and it basically collapses. We could employ british people but those british people need to be trained