We’re relaxed parents. But at that age (3 and 4) you have to very involved with them all the time. You can’t simply let them run amok. Or expect to have an adult conversation while they sit nicely or entertain themselves. It isn’t going to happen. You have to model and teach good behaviour. That means, phones firmly in pocket.
For example, when eating at a table (at home or out), you have to constantly interact with them to keep them entertained and distracted. Talking to them, about their day, what they enjoyed, what you’re going to do tomorrow. Being a bit silly or funny, without getting them hyped up. Kids need humour rather than sternness, at all ages.
Kids that age quickly get ‘ants in their pants’, so you have to be prepared to have them on your lap at the table if they get restless, tired or bored. We used to allow them to have little toys (e.g. little action figures) so they could play little games with them (the salt and pepper often became part of their games). We also always had activity and reading books (especially when eating out) to distract them and keep them occupied and calm.
If they start getting loud or squabbling when out, you have to explain to them WHY they should be considerate to others, e.g. “Everyone wants to be peaceful while they eat their lunch, so we mustn’t be loud, as it’ll disturb them” or “Look, the waiter’s carrying plates of hot food, so we mustn’t get in his way as he might drop it on someone and burn them”. You shouldn’t simply say: “Sit still” or “Stop being loud”. Because little kids need to know why and how they should be considerate and respectful to others. As a parent, it’s your job to teach them.
If they get really restless, or it’s very noisy or hot in a cafe, one parent may have to take them outside to calm them down by showing them things: anything (shop window displays, cars, trees, people going past) to keep their interest, talking calmly all the time.
So, at 3 and 4, both parents (if there are two) must be very hands-on, interacting with the kids and tag-teaming to give each other a breather. We still used a buggy at that age, as they can get very tired and often need to crash out or be simply be contained and calm.
It sounds like your DH is leaving it all to you. They’re his kids too. It’s hard work being with young kids (ask any childcare worker). But it’s also so rewarding. At that age, they’re such a joy, wanting to discover things, wanting you to play with them and needing lots of cuddles and closeness. They grow up so fast, your DH should try to take delight in every minute. In no time, they’re teenagers and you barely get two syllables out of them! Good luck 💐