The thing about laws is that it's not for you to pick which to follow and which to break. It really is black and white, legally speaking - speeding in a residential area is just as illegal as speeding out of town. You may get larger fines, sure - but both are just as illegal.
The Black&White effect is exactly the side-effect of laws, that they can be taken to the letter and generate more complications than they should solve. It is why a person could go to jail for stealing medicines out of need and a man might be free after stealing millions from others just because he found a nice legal loop around a law.
Laws can be very blunt tools, they're just there to set a standard, a behavioural direction, Laws tell the rules of a society and reduce quarrels and fight, but the justice they do is only dependant on how good they are written and enforced, not on the fact that they exist or that you are respecting them.
Also, it's not the law that decides if you've broken it, it's another man who's been given the authority to deicide whether you are breaking it or not. Be it a judge, a policeman, a militia, a priest, it doesn't matter. The law in itself is inert.
Laws can be well written or poorly written. If your only concern is that they are respected, you risk becoming freezingly fierce and cruel, or dowright stupid. And greatly inefficient.
In our speed limit thing: it is probable that speed limits in the US are quite more realistic for residential areas than they are for freeways. That can happen for a variety of reasons, for example the fact that the cars available when the law was set were incredibly less safe, efficient and performant than the cars we drive today. This fact might have had an importantly lower effect on slower road because of the fact that the only real major safety feature that is important in residential areas is the total stopping distance, and that includes the driver reaction time, which at the moment can not be improved and which has an increasingly greater impact (%) on the total stopping distance as you lower the vehicle speed.
Also, 10 over on 65 mph is 15% more. 10 over on 25 mph is 40% over. 10% over 25 would b e 27,5, and there's a very noticeable difference between the 27,5 and 35. Yet, they are both "breaking the law", but do you honestly think that 27,5 mph and 35 mph on a 25mph speed limit is exactly the same because they've both broken the law? Beacuse that is what you say that 10 over on a Freeway and 10 over on a residential area (albeit with different vehicle) is the same.