Hello Esther,
I know your post is quite old but I'm relatively new to this site and have been sick in bed the last few days so loads of time on my hands and wanted to ask you something on this topic.
Leaving aside the argument for/against US and its placebo effect, would you leave a patients side while you had an ice/heat pack applied to them or would you allow a patient to perform an ice cup massage on themselves?
I know these exaples don't have as big a capacity for injury as US does(periosteal burn, etc) but you say never leave a patient. Also if you give a patient exercises and they do them incorrectly whilst unsupervised and injure themselves is it not the same liability as them doing the US wrong after you instructing them clearly in its application?