I don't think it's helpful to jump on the OP when she's explained she wasn't even objecting to those posters or for that reason?
I also see people telling the op that's it's her fault because she didn't react 'right' in this situation, which is rather mean after the nth time in one thread.
Perhaps people don't realise how harmful it is to be told off for reacting wrong by 'letting' your partner be mean/ control you / treat you badly.
It does all rather smack of 'it's your fault for letting him treat you like this', which would make someone feel even more rubbish, especially if the OP is in a relationship that isn't a healthy one.
I have no idea if the OP is in a relationship that is slowly eroding her sense of equality and right to govern her own actions.
However I do know that when I was in my abusive marriage, I found it really dispiriting when people don't 'get' why I couldn't reverse the abusive relationship dynamic by simply saying no in a fiesty way.
It doesn't work that way unfortuneately. And the blank incomprehension isn't terribly motivating as it shows the gap is so large people can't empathise or reach out into that gap to show the OP how to get out and cross the gulf.
As someone controlling goes beyond the social norms people are used to, and people in controlling relationships can't just grab back power unless they are willing to go nuclear and walk out of the relationship.
It takes a while to get to that point and it's not fair to expect the OP to do that unless she has plans in place. And having an exit plan fully in place is a very different situation from slowly awakening to the idea that all is not peachy in your relationship. A person who's willing and ready to leave has already has insight into the abusive nature of the relationship, and wants to get free, and is willing to disrupt the relationship dynamics significantly in order to either see if there's a chance of reshaping the relationship or to leave.
In this case I think the OP really did feel powerless as she hadn't got her own wallet and her partner refused to buy her any food. So what if she kicked him up the arse or tried to order food to be part of his order somehow, all depend on the partner reacting in a way that acknowledges the normal power balance in a relationship. Where showing upset or anger results in consideration and re-evaluation of a decision. A reality where each partner has needs and a voice, where one partner wouldn't really deprive the other of food, or even dream about eating food in front of his hungry partner who's already said they are really hungry and need to eat. In a controlling situation, how can the OP force her partner to acknowledge her needs as equal to his own, and how can she force him not to believe he can control her eating, hunger, weight or basic body autonomy? Saying no just isn't enough. It doesn't matter that its joint money or not, if she has no physical access to money in that moment, and her partner simply refuses to spend any money on buying her the food he wants to deny her. Pointing out the morality of a situation (i.e. It's both of our money, so you have no right to withhold money from me etc), simply doesn't work if the partner doesn't give a shit.
Of course she could have gone back to the car to reclaim her financial independence. Assuming she has car keys and doesn't have to rely on her partner giving her the keys. But then she would have to cancel her dentists appointment and / or trek around with a buggy and child etc. So she was put in a position of put up or the whole day ends up dissolving around this events, and she will need to expend more time & effort to replan everything, I'm pretty sure the partner wouldn't be bothering to wipe up his own mess!
She's put in the position of accepting his shocking unpleasantness, or derailing the whole day, and possibly being tipped into a confrontation she's not mentally ready for. It is, in fact, a very good way of controlling someone!
And each time this happens, the person being manipulated in this way loses a bit of self esteem, independence and equality in the relationship, and the control is normalised.