I take it that you can also be cited for speeding if you are going below posted speed limits under certain conditions, bad weather, unusually dense traffic that's going under the speed limit due to traffic density, etc., though you almost have to have an injured party to get such a ticket.
The problem with "reasonable and prudent" is that it is sort of a nebulous standard that is not uniformly interpreted by different municipalities. A speed limit, on the other hand, is easily definable and exeeding this speed is easily provable in court.
I understand that speeding is handled as a civil and not a criminal offense because civil cases have a "preponderence of evidence" standard of proof instead of a criminal case's "beyond a reasonable doubt" standard.
You can be cited for anything, really.
When you say, "The problem with "reasonable and prudent" is that it is sort of a nebulous standard that is not uniformly interpreted by different municipalities,"
This statement overlooks the fact that these different municipalities are "enforcing" rules against folks upon whom they actually have no legal leg to stand on.
Granted, people who drive fast through residential areas, school zones, etc. should be made aware how they should give more thought to the consequences and encouraged to make better driving decisions. I feel that the use of speed limit signs are a double-edged sword in accomplishing this. They usually offer an appropriate guideline for speed based upon observation of the traffic pattern, and the money extraction aspect of ticketing is a good deterrent. It just seems ever so slightly criminal in nature to blatantly deceive people when the process is painted as if based in law.
As for "preponderance of evidence," well, that part is accurate enough. When prima facie evidence is accepted as fact and actual evidence is never considered, then the preponderance of evidence convicts. Whether this is beyond a reasonable doubt is questionable, as you can argue and present evidence to your heart's content in an "administrative venue" like a J.P. or Municipal court and they have no obligation to consider it. In the end their decision stands.
The term "Kangaroo Court" seems appropriate.
If you are displeased with the outcome there you may appeal to a court of record for a "trial de novo" (new trial) where everything that happened in the admin court is forgotten, and things like arraignment, evidence and other factors will carry weight.
Every aspect of law in Texas is founded on the concept of "common law" where it is presumed that an injured party is seeking relief. Administrative venues are more like third-party arbitration as a way to resolve things before taking the matter to trial.
Only, these administrative justices usually favor the collection of money over things like ethics, morals, facts, etc. and have little working knowledge of the statutes themselves and are often confused by logical presentation of facts. Many seem to prefer to pass the matter on to the county attorney and court than to make a decision that does not favor money collection.
Where you indicate how "exceeding the speed is easily proven in court" it misses the key point of how there isn't any actual statute or law on the books being violated. If there is no injured party seeking relief from damages there is no matter to be decided by the court. They dress it up to look legit, making the State out to be the injured party when the "State" actually has no standing as a "person" in a court.
In many cases speed limit signs give some people the impression that it is safe to drive at these speeds. As if they are in an amusement park where the ride has been made safe for them. So, they drive the indicated speed without consideration for the conditions, or any reasonable assessment of their ability to manage things should the conditions change for the worse.
For these people the existing ticketing system probably works best. It is like the amusement park attendant taking them to time-out for breaking the rules and putting themselves or others in danger.
It seems unreasonable to me that those who are conscientious and practice good skills are punished along-side those who think the rest of the world is there to serve them and keep them safe without them having to think about it.