£10 seems reasonable to me if you're spending unnecessary time in the pick up zone. The charges are very clearly advertised before you enter the area and not only that but EDI revealed these new charges some time ago on their website and social media channels and it also got the attention of local media too.
As you say, Aviation is in the doldrums. Do you expect the airport to run on thin air? They have every right to make money off the very few people who are using it these days. Why on earth would you expect Otherwise?