Say you let the people decide, it still wouldnt make a difference because that what a jury does. If you would make every single case in the country a sort of referendum like vote, it would then be very easily influenced, and thus not be impartial and fair like how a legal system should work. Imagine this a murderer is on trail, he brutally killed 5 people in a maniac rampage, but hes a massively succesful tiktokker(ew) and says hes very very sorry and it won't happen again. Do you maybe think the results would be skewed in his favor due to his massive fanbase? If no, you are oblivious to how easily people are manipulated.
The peoples vote is inherently objective and never impartial. The law exist to try and remedy that so that everybody is treated fairly. Also do you really want someone in power where its proven that they laundered huge amounts of money to themselves? Thats just a recipe for disaster.
Thy end is now!