Kill a cyclist, get community punishment

your third point assumes that cyclists are some sort of underclass and considered as "the other" or the usurper

I'm not assuming it. I'm stating it based on the huge number of "they don't even pay road tax", "get to the side of the road", "lycra louts" and "let's string up piano wire" statements you can find in tweets, videos and even broadsheet newspaper articles.

Also "outgroup" is a specific term in sociology, referring to a known set of psychological biases applied to (and demonstrating that) a group seen as "other". For example "Out-group homogeneity" in which an outgroup is seen as all the same e.g., "all you cyclists jump red lights". You demonstrated this yourself when you said

I also think and this (goes for myself included), that if you want more sympathy / empathy from motorists a lot of cyclists have to behave better towards them and people have to be more responsible e.g. not going out for a load of beers and riding back pissed, riding with no lights on riding on the pavement ... because the first fucking thing people will say is "Well cyclists don't follow the rules either, I saw one doing the other day".

That is exactly one cyclist being damned for the actions of another, even if they've never met them.