the significance of knotweed being?
any fragment of it picked up wheels / clothes / shoes will start growing again wherever it lands so where its by a busy path / trail / road it will spread rapidly along the route and to other places those people visit and as said above if you take bits home with you and it takes hold it can compromise insurance or mortgage-abililty or yours and your neighbours houses.
Once you have it on your property getting rid of it is very effort intensive – it takes year and years of treatment – you can be fined and face criminal prosecutions for not dealing with it, you can face prosecution for dealing with it incorrectly and if in trying to dispose of it you ‘allow it to spread’, for instance by transporting it and losing any of it on the way, can result in bigger fines and even prison.
On the plus side the young shoots can be cooked and eaten in a similar manner to asparagus. 🙂 All be it with a bit of tang of several years dousing with glyphosate.