Seems we have moved onto a whole new area here, in talking about discipline..... 
I was a long way from perfect ...... and also, I think, lucky ..... but have always said that if you don't have a child "where you want them" by the age of 5, then you have little hope of a respectful relationship when they are old enough to really argue back. The definition of that, for me, is that a child does as it is asked to do, and that lesson is learned very early on.
For me, it meant teaching 'action & consequences' from a young age. I did smack very occasionally in the 2-5 years but I never (hand on heart) smacked in anger, and my girls always 'chose' the route in that I would ask the child to stop whatever it was doing, I would ask a second time with the rider that if you do that again, I will smack. Third time, I smacked once on the leg or the hand ....never hard. It was not about pain but shock factor, & following through on what I had said, and I could probably count all incidents on two hands.
It was a rare event, and all about consequences if a line is crossed
By school age, I could just start counting to 5 .... and never once got there!
I do think though, that there must be a basis of mutual respect. It is a two-way street, and it is possible to ask children to do something rather than ordering, and possible to discuss rather than having to completely control every aspect of life. Both my girls were expert negotiators by the time they hit their teens. They had choices from the earliest days ^ (red coat or blue coat? shall we go to this shop or that shop, first? you can have pudding if you eat your main course). ^
Two things make me smile to this day 1) that my daughters were both almost adult before working out that I always started negotiating way higher than the point I was happy to settle at. 2) that they both now adore sprouts, having spent years with a negotiated 'just one' or their plates 
As said, I was (and am
) a long way from perfect, but I do worry when I see mothers who can only control toddlers with violence and abuse - or fail to control them at all.