Do they really have to "interview" people who already work for them?

Yes they do - due process has to be followed in a redundancy situation in order to stay out of court afterwards.

Other people I know have experienced the same thing - it costs money to work!
No commute (£5k of my pre-tax income). No "business formal" clothes to buy.

I have been through five redundancy rounds, been made redundant twice and had my job downgraded once (luckily HR were so incompitent that they forgot to cut my wages to the lower grade on that one). Trouble is that the stock markets used to view redundancies as a sign that a company was in serious trouble, now they are taken as a sign of prudent management.