They don't go for exact score ante-post bets. They gamble on wins/draws/defeats with + or - goals, with odds changing as the match progresses and the score changing.
"Industry insiders believe the worldwide online sports betting market (which operates mostly from Eastern Asia, which accounts for an estimated 80% of their activity) to be worth 1 trillion US dollars in terms of bets placed, of which 600 billion US dollars are thought to be wagered in China alone; give or take a billion or two, roughly the combined GDPs of Sweden, Finland and Norway."
http://josimarfootball.com/the-trill...gambling-game/
Of course no-one is suggesting that LOI Championship football is a focus for this trillion dollars(!), but even a minute fraction gambled on a minor European soccer league, or a youth tennis tournament in Argentina; or Kenyan basketball, or even two cockroaches crawling up a Hong Kong wall will attract these gamblers, since they don't give a stuff about the actual event, just the chance of winning.
And as the above article points out, events like the English PL are just too big, too well regulated and too scrutinised to be able to fix them.
Add in money laundering , tax evasion and the organised crime generally behind these sites, and you have ample motive for them offering odds on eg LOI football games and their customers for having a punt.