My experience has been that things go much better when parents set clear boundaries. If it's sometimes ok to pick the flowers and other times you get told to stop, there's a lot of trying to figure out what makes these particular flowers or this particular time different from others. Some complexity is unavoidable (you can't pick flowers from the neighbor's garden, you can pick all the dandelions you want) but a parent who's not thinking about it can accidentally make things harder for their kids by being inconsistent (only sometimes stopping them from picking flowers that shouldn't be picked, not making up their mind about which flowers are ok).

With very little kids, what matters is what happens when they try to pick the flower. If you don't stop them, that's some information about what's ok; if you do, it's some information about what's not. Kids who are a bit older are smarter though: they care about whether you've observed them. Picking a flower without objection while being watched is a signal that the flower is fine to pick, but picking a flower while not being watched doesn't actually tell you very much about what's ok. It does tell you a little: it's probably not so hugely bad to pick flowers that a sensible adult would continue supervising. But mostly they understand to only update their model of the boundaries the adult is enforcing when the adult is paying attention.

Which means, very occasionally, you might want to pretend to not observe something. If they believed you'd seen it, you'd need to enforce the boundary or they'd think it had changed. But by pretending not to notice you can give them close to "no signal", as if you weren't there at all.

For example, let's say you have been enforcing a clear "no hitting" rule, and your kid hits an older kid, someone mature enough to stand up for themself. With the boundary you had been enforcing you would need to step in, but, if they both believe you didn't see, they can get practice in resolving their dispute independently ("Don't hit me!") or at least in bringing their concern to you ("Alex hit me!"). This could be part of a process of moving away from a toddler's "hitting is not allowed" to a Kindergartener's "hitting is not allowed, but try to work it out on your own first".

The most blatant forms of this stop working in, maybe, early elementary school, once they get smart enough to either put together patterns of when you don't seem to notice things, or learn what you look like when you're pretending not to notice. You probably can't actually give no signal to a sharp-eyed child; I know I can't. And it stops working earlier the more you do it, because they'll have more chances to learn your patterns.

I don't like that it involves misleading them slightly, but doing it occasionally in ways that help them grow seems positive on balance.