The problem is when no one else can maintain or source parts for a specific elevator the OEM can hold the customer hostage and charge whatever they want for service. I've even a seen some OEM not cover certain propriety items like belts and drives from their full maintenance contracts so they can charge for a repair only they can do. Also depending on the area some of the OEMs provide completely awful service. So if no one else can maintain the equipment the customer could be stuck with horrible service and crazy high prices for the life of the elevator...all of a sudden the extra $$ upfront doesn't seem so bad.