DSS was not left unattended until he was 3 maybe 4 (when he was with us)
As we did nt have him full time it was easier to concentrate all your time and attention and so it was something that we didnt do.
MJ is almost 16mths and it is harder with her as we are together all day...I stay in the bathroom with her, however I will duck out to grab a towel if i have forgotten to grab it. But we have a small house and i wouldnt actually go and 'do' something while she was bathing...
I use the time that she is in the bath to clean and tidy the bathroom... or i bring in washing to fold or i wash my face and put on a face mask twice a week... OR
DH has a bath with her and i get to do the tiding!!! But most of the time we play together...
ETA - MJ cannot touch the taps, when we reno'ed we made sure that they were located too high for a toddler to touch.
Claire at the age of 10 there is NO WAY that DSS was comfortable having us in there with him. By 6 he wanted to play totally alone in the bath - not because he was embarressed, just he enjoyed playing alone (thats sounds rude doesnt it - i dont mean it in that way thou

) I know what you are saying about the safety, but i think 10 is not reasonable given that children do start to like their privacy... i wouldnt go out of the house thou when he was bathing - we are always in earshot - even now and he is almost 12