Its all about risk tolerance.  The risks aren't Zero.  They are, in my view, Negligible.  With reasonable, normal, routine levels of care.  Extreme efforts can't reduce that risk to zero, but may reduce it some fraction of a fraction of a fraction of a percent.
Similar to the risk of getting a food born illness from fresh produce at the grocery store.  Sure, plenty of people do each year, but when compared to the number of times each year roughly 300 million people in the US eat fresh produce...  and its pretty clear from public bathrooms that some of those people have differing levels of acceptable daily sanitation, which we can only assume applies to their food prep efforts as well.
Whether the additional care, multiplied by that negligible risk, is worth it to you or no is a factor of how you value your birds.  I value mine, but they aren't pets, and they are replaceable.  If the flock gets culled, I'll be irritated, financially harmed, but not devastated.  Your own calculus almost certainly differs.