There's I believe one example of that in the us and they were charged under the relevant currently existing law that makes willfully blocking emergency vehicles a crime.
Do you understand the difference between accidentally doing something wrong and being negligent and causing harm? Like you get that if I swing a bat around in my backyard and someone sneaks up behind me that is a lot different than if I swung a bat around in a crowded room?
Scale: one car contributes almost nothing to a traffic jam
Intent: a person driving somewhere is trying to drive somewhere. A person abandoning their car or standing in the road is trying to, in the words of people ITT, "causing inconvenience" and getting people "angry".
Flexibility: if you are in your car and see lights flashing you can at least try to get out of the way. If you have abandoned your car to cause a jam you can't.
You really can't have it both ways. You can't claim you are trying to inconvenience people and bring attention to your pet cause while also claiming you are just doing what normal people are doing.