Kill a cyclist, get community punishment

Look I dunno how this is hard to understand.

It kinda like saying all cyclists are environmentalists, because cycling is good for the environment and therefore they will all vote for the green party. You are inferring so much when you don't really know.

Well you don't seem to understand it. You're making a hypothesis (all cyclists are environmentalists) and then ignoring the fact the evidence doesn't support it (because cyclists don't all vote for the green party).

What everyone else is doing is making an observation (juries regularly acquit people who, according to the preponderance of evidence, have caused death by dangerous driving) and looking into why this might be the case based on known facts:

• juries, simply by the laws of probability, consist of people who drive
  
• juries, simply by the laws of probability, consist largely of people who don't regularly cycle
  
• cyclists are treated as an outgroup by many people in society (evidence from social media, TV, other media)
  
• driving is considered a default behaviour (including bad driving)
  
• people are fallible and often subject to biases (years of psychological research)
  
• conclusion: it's possible to infer (although completely disprovable) that jurors are biased towards being lenient to drivers in cases in which an impartial observer would convict.