But WHY was she hitting? Did anyone figure it out? Obviously she has something to "say" about how she feels about something but doesn't know how to do it in a socially acceptable manner yet. Did anyone tell her how to fix that? So it starts becoming more socially acceptable?
I guess I don't see how taking a bike away at 4 models the HOW to say it in a socially acceptable manner (whatever it was) and then how to cope with it. So basically she's still in the same place AND minus the bike that helps you exercise.
You way is kinder, but it's still all about you. How you feel hurt, hitting is not nice, etc. So you would still leave her in the same place, and take away her hitting coping tool from her coping box rather than the bike.
Who is putting better coping tools IN to her box? Telling her what TO do, rather than what NOT to do? So we can leave these childish coping tools behind?
When mine was in the hitting place we played the broken record like the weather channel -- "You are MAD. You are being like this (copy the kid shouting hitting whatever). That's not cool. You may NOT hit alive things like the dog or people. If you want to hit something, you may hit your drum. You may stomp your foot. You may mad angry pictures to get the mad out. Get it all out, then we will talk again."
Just like in babyhood for the weather channel of general vocab -- See the DOG? That is a DOG. Can you say DOG?
Only this time is feelings -- You are MAD. See how MAD is -- shouting, fist clenched, etc when you copy the kid. Can you see this is MAD? Now can you do something about this MAD that is more acceptable? (list that you prefer she can actually do at this age like stomp foot. It can refine later. Just bump her up one level to a more acceptable thing than toddler stuff like hitting. I could live with a foot stomp for 4. At 8 she's not bothering to foot stomping any more, she just TELLS me she is mad. )
So my kid would stomp and/or draw angry pictures (I saved some of mean mom with a big black X scribbled on top -- it's hilarious) and then later we'd talk. Sometimes she would have forgotten about it already by bed time and she'd be all "I did that? That's silly."
Later we added emotional price tagging. Making a great big noisy fuss (Like Ramona Quimby in Beezus and Ramona) over everything was not wise spending of feelings. Stub your toe, that deserves an "OW!" sure. But not the same amount of upset for losing your favorite teddy bear for 3 days. Too much is to much.
I don't know if those ideas help.
I'm glad though that you have agreed to move as the United Parent Front in future for discipline. That's a prob for us here too sometimes -- because kids catch ya off guard. But def before you parent the kid, you parent yourself.
Sometimes I would just tell her "I am upset. I am MAD that you did this. I do NOT love this. I love you always, but i do NOT love this. So I am putting myself into time out to think it over and sort my feelings out first. I need to cool off, I'm in time out. If I deal with you now I will be unfair to you because I am mad. I still love you, but I do NOT love this. So shoo and get out of here! I'm in time out and I'm REALLY MAD. We will talk at bed time."
I want to model that we don't hit, I want to model that even I lose my lid? I want to model how to lose it more gracefully. (I do not always succeed and sometimes I pitch a fit just to pitch it. See Mom trying to lose her lid well? See mom losing her lid NOT so well?)
And it doesn't hurt that if MOM has to put HERSELF into time out, whether she loses her lid gracefully or not? Whatever thing you did is PRETTY DANG BAD KID! Everyone is all "ohhhhhh.....nooooooo!" Which serves just as well or better - hahaha! I get a quieter afternoon.
Your DH hanging out punishments in 2 seconds -- he may want to work on that. If he always punishes and never listens, how's he teaching
to future? Like when she's a teen and has bigger teen problem than some 4 yrd old temper tantrum?
Or will he have taught her along the way that "Talking to dad is useless. He just cranks up and hands out punishments at the drop of that hat and never listens to me? Or guides me?"
Because that is the biggest thing to parenting -- guiding these immature people (children) into maturity.
Hang in there!

A.