One real-world constraint is that end-users won't always do what you intend for them to with the thing you engineered.
“Letting everyone out of prison is a good social strategy, it’s just hard to prevent people from abusing it.”
“Making all shops operate on the honor system is a good business strategy, it’s just hard to prevent people from abusing it.”
One real-world constraint is that end-users won't always do what you intend for them to with the thing you engineered.