Just as well there was no one underneath it, or some prized possesion
of the owners...

Not thought of having a leash attached to such tools when working at
heights?

I use a lanyard when there's a particular increased risk of dropping a
tool - but you simply cannot do this for every tool, brick and drill
bit.

Tidy working conditions - good. Toolbags/buckets - good. Toeboards if
it's a proper scaffold - good.

But unless you're going to work like NASA, at a snail's pace and with
every movement pre-planned - drops will happen.

Oh but - even they've dropped toolboxes and wrenches off into space.