Agree! No excuse for this behavior.
My mother gave me baths through age 4, after which time I bathed myself and enjoyed playing with all my bath toys. At age 8, I was ready to start showering, and my mother stood outside the shower, fully clothed, and gave me moral encouragement because, well, it was a bit scary. After a couple of times, I did it by myself.
This is how it is done in normal homes. My dad had different jobs - like teaching me to ride a bike. Not teaching me how to take a shower! And besides, there’s not a whole lot to teach anyway.