Did you look for an intercontinental flight? They've been showing booking classes for quite a while for those flights - if you know what to look for (most passangers don't). I tried to look up prices for OSL-LON from www.sas.fi and no there was no possibility for me to see my booking class before confirming payment.

The problem is not only that they don't show the booking classes, but that they don't let you decide what booking class you want to be in (25%-earning, 100%-earning etc).