I've seen,and been in fights where either one girl submitted or was knocked out,and most of the time,there are others around watching,where it be other girls...friends of the fighters,or a crowd from a spontaneous fight that broke out,rarley is it alone,in private one on one.
I had one private fight in all my fights,and before we even met to fight,we met a few times at different locations to get to know each other better,warm up to each other,so there was a little trust there when we did fight.
And this was about a three month time span until we fought.
When it comes to Lawsuits,or liability well, it's more like 99.9% of the time,they don't exist,and if so, most are thrown out of court anyway (i know,i work for the court system).