Yeah this gives you an advantage in choosing a team and depending on the live match whether there has been a goal or not? Then which team is dominating the game then this can change the odds so quickly with its changes.
I don't think this is a trap but can judge the game directly in progress from before it starts.
Some people still like to bet while the match is in progress this gives them an advantage maybe a solid bet.
It means, you bet on favorite team when they're in advantage? why not just bet in pre-match? the odds in live bet would be lower than pre-match because it's a favorite team and they're in advantage position.
If I want to bet on favorite I will bet before the match starts.
Most of the time I bet in live because I hope the favorite team to comeback.