Bet365 can say to regulators that they have banned players for gambling too much....in reality it is a way to kick people out who are a threat to their bottom line. Most British books have a very low tolerance for winners. Those that have pretty good businesses in non-American locations line the pockets of the regulators and politicians to keep out the better bookmakers.
Now in Australia, they've managed to kick a subsidiary of pinnacle out of the country offering pinnacle-type lines and have gotten legislation passed to ban Aussies from betting in overseas more competitive lower juice bookmakers.
Because of that Australians are typically given non-competitive lines....for example >22 cent baseball lines.
Matchbook and betfair have a liquidity problem with USA sports...there's not enough bettors betting enough money in those markets....plus in non-USA markets moneyline betting is much more prevalent than pointspread betting and it can be difficult to get matched pointspreads offers....and one may wait until game time to know whether they have a bet on, or not.
To bet on rugby league, British soccer and Aussie Rules is no problem, plenty of bettors and money in those codes.
The most aggravating thing about betting in Australia is that books rarely have a stated betting maximum. The process goes like this.....
Me: I would like to bet 2000 on an NFL game.
Customer service at book: Who do you wish to bet on?
Me: I'd like not to say, what are your betting limits for the NFL on sides?
Them: It all depends on the game you want, who do you wish to bet on?
Me: Are you going to change the odds after I tell you who I want to bet on?
Them: Oh, no we wouldn't do that. Make a deposit into an account and we will see what the management says about your bet.
Me: I don't want to make a deposit if my bet isn't going to be accepted, ok?
Them: Sorry (they're not really sorry at all) that is the company policy. You can make a deposit and then we'll see if it is accepted.
Me: I'll go elsewhere then, good bye (and thanks for wasting 5 minutes of my life that I'll never get back!)