William Graham used his keyboard to write :

One of my cats will not bury her droppings, she leaves them on the top
and I have seen her piss in the street.

I disagree.
Cat's by their very nature, will always dig and bury (hide) their wastes,
and rarely defecate in their own "yard".
Unless they have absolutely no other choice.
eg. the complete yard is concrete or asphalt.

Often they can even be trained to come inside to use their litter box and
return outside.
Or a weatherproof outdoor litter box may be an option the OP might think
about.

However the advice that kids should be taught to wash well and often after
playing outside is good in any case.
As several other replies point out that cats are not the only critters out
there.
And that includes OTHER PEOPLES cats.

Mind you,....I have never heard of any kids actually dying from stepping in
dog or cat feces.
And plenty of kids played for years outside with little or no harm.

My father had an old saying that you had to eat 10 pounds of dirt before you
died.
Which was more a reference to "don't panic over something unimportant"

I'd be more concerned about the kids playing with old hypodermic needles, or
China made toys,  than a wad of cat sh.t.