Actually, you're wrong there - Germany uses a similar system on the first levels of the justice system [1]. However, we have crucial differences to the US:
- we don't have that ridiculous requirement of jurors having to lock themselves away for fear of getting a contaminated judgement [2]
- while we do allow participants to contest the jurors, it's rare for such motions to succeed, except if there is substantial evidence for bias
[1] https://de.wikipedia.org/wiki/Sch%C3%B6ffe_(ehrenamtlicher_R...