This is because they are trying to parallel like 50amps (it's 12 volt IIRC) over a few conductors to get to 600watts.
If it becomes unbalanced due to any number of reasons, none of those individual cables can come close to handling it - they will all generate enough heat to melt lots of things.
Conservatively, they'd have to be 8awg each to be able to handle the full load without melting if they ended up taking the full load onto a single conductor.
That's the crappy part about low voltages.
If the voltage was higher (i believe 'low volt' classification tops out at 48v), it'd be more dangerous to deal with in some aspects, but it'd be easier to have small cables that won't melt.
If it becomes unbalanced due to any number of reasons, none of those individual cables can come close to handling it - they will all generate enough heat to melt lots of things.
Conservatively, they'd have to be 8awg each to be able to handle the full load without melting if they ended up taking the full load onto a single conductor.
That's the crappy part about low voltages.
If the voltage was higher (i believe 'low volt' classification tops out at 48v), it'd be more dangerous to deal with in some aspects, but it'd be easier to have small cables that won't melt.