I've traveled full-time for 8 years in a carnival (my husband for about 11 years) and everyone I know, from tiny little bumper-pulls to $500k coaches, puts their toilet paper in their trash can.
We do it simply because that's what I've always been taught and seen in practice. It's what we're used to.
Whether someone else flushes or bags, it makes no difference to me in the least. It's not my trailer. I'll continue to bag.
I do like that one person's idea to use cheapy sandwich baggies to.contain the paper, smell and all.