Aren't most systems in caravans controlled by a pressure switch? If a pipe comes loose in a caravan then no system will stop the caravan being flooded.
What you suggest is true, but the scenario you describe is more of a poor assembly process by the caravan manufacturer who has failed to make all the joints correctly, so the system is predisposed to a failure even with the inherent lower pressures developed by submersible pumps.
A correctly assembled caravan water system should be able to withstand a pressure of about 2.5 Bar, so even if a pressure switch failed and a submersible pump was running continually, the system should remain leak free.
There is a greater risk if the water pump is a diaphragm or positive displacement design, where the peak pressures within the pump will be much higher, but the design of the pump is such that the pulses of very high pressure are of short duration and are normally moderated by the volume of the plenums inside the pump and the pump's built in pressure switch, along with the elasticity of the pipework in the caravan. If the pump's pressure switch does fail (and there are known cases where this has occurred) the pressure in the caravan pipe work does increase and the pressure release valves on some appliances are good enough to vent the the excess pressure and prevent system damage.
The most significant dangerous difference between any caravan water pump and a direct supply from mains, is the ability of a mains water supply to consistently exceed the safe working pressure of the caravans water system. This is why direct systems need to have a pressure regulator ( not just a flow restrictor which is a very different device) It is essential the regulator is as reliable as possible, and in general they are statistically very reliable, but there have been failures which have resulted in a combination of excess pressure and flow which has overwhelmed the excess pressure relief valves and allowed the whole system pressure to climb and cause either a product or pipework failure.
As I have stressed in previous threads these failures are rare but the consequences when they do arise are major, which is why I have personally come to the conclusion it is safer to use a water barrel with a float valve along with a submersible pump which cannot exceed a caravans safe working water pressure.
Ultimately it is up to each individually user to decide if the albeit low risk is worth it or to eliminate the risk entirely by using a water barrel and float valve.