Do you believe you should be forced to drive bang-on the posted speed limit everywhere?

It is wrong to drive needlessly slowly enough to be considered driving without due care and consideration for other road users, and I think in Britain there have been occasions of motorists fined on that.

The charge is the "due care and consideration", or causing an obstruction; not driving slowly, for the law and indeed good driving expects driving at a speed safe and suitable for the conditions, within the maximum speed limit for that road. Even if well under that limit.

In a sense, there is a minimum speed-limit on the motorways here, in that certain classes of vehicles that could not possibly and safely keep up with the general traffic are excluded from using them. These classes are pedal-powered cycles, mopeds (pedal-assisted motorcycles not able to exceed 30mph), horses and horse-drawn vehicles, agricultural vehicles, learner-drivers... and of course, pedestrians.

I don't know about elsewhere, but in California the speed limit laws are constructed so reasonable driving conditions take precedence over posted speed limits. So posted speed limits do not take precedence over driving conditions.

In practical terms, most traffic enforcement usually allows 5 miles over the max posted before stopping anyone (IF they stop anyone from speeding, which is getting less and less frequent), but it can be lower if conditions are bad. And vice versa, if you are substantially below the rest of traffic, you are subject to being stopped even if you are within the speed limit.

The primary issue(s) here are you can be doing 5 miles above the max and you will have an entitled Tesla, Lexus, etc., driver running up your trunk and there is little traffic enforcement because police departments are understaffed and traffic has lowest priority.

There are minimum speed limits on interstates