Humans haven't needed horses to travel or to move goods for over 100 years, and nowadays the roads are so busy that they have not only become a hazard, but they disrupt modern transport routes.
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I believe horses are an out of date mode of transport and their use is no longer fit for purpose.
Horses are not only a hazard, but they cause traffic to slow down, fuelling congestion. It's also cruel to subject the animals to both pollution and the scary sound of cars.
The British Horse Society statistics show that from Nov 2010 to Mar 2019 there were 3,737 incidents reported. 315 horses and 43 humans were killed on our roads. The use of horses should be limited to private property, either entirely or at least during peak traffic times.