I’d argue that if it’s a feature of the unit that was present when someone signed, then yes it should be required to work.
Of course contracts can’t cover every little thing, so it’s ridiculous to rely on them for that level of granularity. Do we need to mandate contracts have an Entry for every feature of every appliance, every piece of infrastructure, every piece of structure? No. These things were presented as being there and functioning. But we should be able to rely on things working as presented. We should have a legal right that that be true