Personally I think only a$$***** don't pickup their steel casings, the range has to be swept after the match and everyone is requested to do their part. If your not willing to do your part and clean up your mess, well I really don't need your entry fee that badly.
As a Match Director, I will organize the stages so that there is minimal possibility to damage my steel. If you can't get 10 years use out of AR 500, you are doing something wrong. On the flyer I send out I always request that shooters use lead bullets as this also minimizes richocets.
As a shooter, I have been to matches where targets have been set heavy, and others where they are set light. The majority of the shotgun ammo I shoot is either 7.5 or 8, but I always have a box of #4 in my gun cart and 4 rds of #4 on my belt in case I end up with a couple of targets that are set heavy.