The McDonald's case was actually a serious incident. McDonald's had prior notice that several hundred people suffered burns because it's coffee was too hot. There is a documentary about the case that is worth watching if you can find it. I think it ran on HBO a few years ago. As for the rest of your question I can't answer for other lawyers and can only assume they either think you don't have a case worth pursuing or the damages are too small for their office to handle. Law suits take up lots of lawyer time and money to pursue.
The above answer, and any follow up comments or emails is for informational purposes only and not meant as legal advice.
Sometimes you know in the first minute of the phone conversation that this is not a case you are going to take. Sometimes you know that the case is not within the area of law in which you practice. Sometimes you know in the first minute that you don't want to work with the person as a client. They tell you that they want a "pit bull" or they want retribution. There are a great many lawyers and lawyers don't have to advise every single person who seeks advice. Sometimes you know immediately that you are not the right lawyer. By the way, many of those prisoners file their own cases or are helped by people right there in the prison who have legal experience and ability. And don't get me started on the McDonald's coffee burn case in which a woman was severely burned by coffee spilled in her lap after McD's had been cited hundreds of times for coffee served at scalding temperatures. It's easy to cite that case as an abuse of the legal system, unless you know the facts.
You are clearly misinformed about the McDonalds coffee case.
It is likely you are equally misinformed about the validity of your case and/or seek something the system cannot provide you. Both are valid reasons for an attorney to decline your case.
The foregoing is for general information purposes and does not establish an attorney-client relationship.
Your "question" in a sense is a rhetorical one because no one on AVVO has knowledge as to why you were declined representation by other attorneys. Many possible reasons for that happening have been suggested by other responders. It is respectfully suggested that before you allow yourself to become bitter based on a belief that other "cases" which you believe are questionable or frivolous in merit have been brought so why not yours, you should be aware that, as a general concept, more cases have been "turned down" by attorneys than have been "accepted" or taken. Additionally, even if you found a lawyer to take your case, there is no guarantee that yours would be successful if you could not meet the requisite showing of entitlement under the law. If you did a little research, you would find that many a case has been disposed of by a defendant's verdict dismissing the claim - even some which could be considered having the color of meritorious argument. As such, attorneys have to always consider which case to invest time and effort into, which is a personal decision for each attorney. After all, our system entitles each person to choose which lawyer they want to hire; and the lawyer is entitled to choose which client they want to represent. Fair is Fair.