Why should this be any different with computers? The risk that you pose to others is pretty low, so there shouldn't be any requirement to have a "license". But I wouldn't call it arrogance, if I'll assume that someone using the network has a minimum knowledge about how things work.
Only to a point. I own a car and am perfectly competent to use it, but I have only the vaguest of understanding as to what things like spark plugs and catalytic converters do. I know what a manifold is in mathematics, and I suppose it's a bit similar in a car engine. I deem myself knowledgeable to open the bonnet and add windshield wiper fluid when that's low, but anything more complicated I'll take to a mechanic.
> If you're using it without learning how it works, it's your own fault, if you have an accident.
It's my fault if I drive without, say, learning how to operate the brake pedal, or learning how to turn on the turn signal. But if the accident is due to something wrong with the internals that I know very little about? I don't think any reasonable person believes that getting licensed to drive should require one to have the knowledge of an automobile mechanic.
Browsers have no way of deciding which cookies are tracking and which aren't, and disabling them all causes all kinds of problems, including with sessions. Legislation, on the other hand, is less 'blind' and lets websites using cookies for functionality the user required and/or is informed of (like sessions, preferences and such) without letting websites perform unauthorized tracking.
That's the same problem we have in the EU right now. The correct way to deal with cookies would be for people to enable or disable them in their browser, according to their personal preferences. Instead, the EU forces their cookie legislation on everybody, because most people are too lazy to fix their preferences.