With my team, we split payout among anyone who lines up for the race. But, guys are not required to take the money if they don't think they deserve it. We make this clear to everyone joining the team so there is no discussion or hurt feelings later on.
And for races we put on, our goal is to get as many guys on the podium as possible to protect the purse. We do not get payout in our events. At the same time, we don't pay full entry for the races either - it's $5 to race all day and that is to cover our costs (insurance, USAC and and LA fees...) for each racer.