There is often a poor understanding of terminology that surrounds ragwort. This is a case in point. It comes from this site, which falsely states
It is important that any specialist is familiar with existing legislation such as the Weed Act 1959, which stipulates where action must be taken to guard against injury from weeds such as: Ragwort, Spear, Thistle and any other weed type that is acknowledged as being able to cause harm or injury.
To start with it is the Weeds Act 1959 and the plant is Spear Thistle but ignoring those typos it is clear that that particular act of parliament says nothing of the sort at all. It just gives the government the power to order people to control certain weeds. These weeds do not cause injury but are called "injurious" weeds. This word means harmful to the interests of something. These days civil servants would not use words like this as society has changed and fewer people study Latin, from where this word ultimately comes but it doesn't stop people jumping to the wrong conclusion. For a fuller explanation see this Injurious weeds explained.