I worked for magazines and tabloids years ago - regarding the payments that someone asked about, with 'women's' mags, the hacks would be offered a fee; it was then up to them how much they offered the person they were writing about. If they could get away with not giving them anything, that was seen as fine. They would also then try to sell it to other outlets, or, if it was picked up by DM, sell more stories directly to them.
DM wasn't quite so bad back then but there were still angles you had to take. The fees were much, much higher than anywhere else - up to ten times what I'd been paid at some broadsheets. The DM also tended to buy up lots of stories even if they didn't use them, so no one else could run with them. You could make more money having stuff not printed by the DM than having a full time job at other papers.