I call BS. No, I don't jest. But you don't know what you're talking about.
Any officer using emergency equipment and exceeding the speed limit just to go to coffee, doughnuts or lunch would not be an officer long. That's an unauthorized use of authority, abuse of power, and an ethical and professional violation sufficient to bring about penalties up to and including termination and revocation of peace officer certification. It is a very sensitive issue that is treated very seriously and policed very closely.
Sure, there might be a crazy in uniform for a short period of time who might try it once, but there are so many checks and balances it can't happen on a regular basis. Put your money where your mouth is ~ call it in and make a traceable complaint about it, if it really happens 'a couple times a week.' Either the officer(s) won't be officers long, or you'll be brought up on charges of filing false reports. Either way, we will then have some proof - one way or the other - of what you allege.
In the interest of giving you some benefit of doubt, however, I will add that citizens sometimes misinterpret what they see. An emergency vehicle (even fire trucks and ambulances) sometimes rush to an emergency call with lights and sirens activated, only to be cancelled while en route, for any number of reasons - the emergency turned out to not be an emergency, someone arrived sooner and neutralized the emergency so they canceled other responders, etc., etc. Citizens ~ like yourself ~ who are not privy to the radio traffic regarding the emergency only see an emergency vehicle suddenly discontinue Code response (lights & siren) and resume routine activities. Citizens ~ like yourself ~ who don't know any better sometimes jump to erroneous conclusions about what they saw.
And, PS: Hate to bust your bubble, but few jurisdictions ~ if any ~ require emergency lights or siren operation for lawful operations or even emergency response by law enforcement officials. So, just because a law enforcement vehicle is traveling fast but without lights & siren operating does not mean the vehicle is not responding to an emergency.
In fact, I told my deputies that they often could make better time in an emergency response (especially during daylight hours) WITHOUT the lights and siren. Proven. Even the ones who doubted me tried it and found it often true (especially in light to moderate traffic). So, my guys and I tried to stay away from the switches. Did some of our citizens ~ who didn't know any better ~ think we were screwing around? Perhaps. But we also surprised many burglars and interrupted many assaults and captured many, many bad guys who would have fled long before we arrived had they heard us coming. The citizens who may have assumed we were going to KFC for lunch benefitted by our effective tactic whether they understood it or not.