It’s an interesting question and an interesting belief system too.
Likened much to common courtesy and privacy laws in our physical society, this is considered also applicable by many to the psychic and healing arts.
In fact, you will also taste a sense of derision, perhaps judgement – to any of those who might be ‘doing the wrong thing’. You might hear about all the ‘right’ reasons – ethics, boundaries, consent. Like legal jargon.
But how do you know that waiting for permission is the right thing to do, or going ahead with the reading/healing regardless? Truth is that you don’t.
You can only discern the consequences of your actions & act accordingly to the consequences you are willing to accept.
There are always exceptions to the rule. Each individual case is different. What would you do in a comatose case? Wait for them to wake up? Would you consider consent not necessary then?