It would be an insult to the entire empire for the empress to work as a guard. I cannot ex...

I know but this story clearly doesnt take itself too seriouly. I mean the ML invented a day call Steam Bun Day lol.
Chill

Sigh... Food based holidays aren't abnormal. You're comparing different things.

Writing should be held to some standards. All writing. One of the most basic standards is that it needs to be logical. Readers should be able to believe what's written is something that could actually happen. This is why world building is actually really important for fantasy, because if you build a world where impossible things could actually happen and then the reader will believe those things could actually happen.

It's much harder to do in depth world building in a manhwa, especially one that's so focused on romance rather than the world at large (this is actually why Turning is so special!). This means that authors will often rely on tropes or known quantities within the world to make it easier to establish their world building. This is why historic settings are so popular, in a historic setting we all sort of understand how the world works so you don't have to explain it. You only have to explain the extra fantasy stuff you're adding in.

So far there's been a little bit of fantasy with the rules of the worlds, but there's also been very clear hierarchy. The emperor has shown again and again that his orders must be followed. The guards follow his orders and are subordinate to him. The guards have also been shown to be subordinate to other nobles because they are workers first even if they are nobles otherwise. This is established world building that the author has demonstrated.

Now the author is taking that world building and throwing it away. They're throwing away the historical context that comes with the setting and they're throwing away what they've already built... All to make the empress a worker. Which means all of the established hierarchy and authority and this entire empire is garbage. The empress has no authority. The emperor has no authority. Now the guards tell the emperor what to do. Now, somehow the emperor and empress are subordinate to the guards and the workers order the emperor and the empress around.

You're not wrong to say that I should just suspend my disbelief but I'm not just pointing out that it's not believable, I'm pointing out that this is a fundamental mistake that the author has made. This is bad writing.

They actually used to teach you to analyze everything you read this way in school. The degradation of our education system is a travesty. This sort of writing shouldn't be defended but instead should be criticized and used as an example to better your understanding of better writing.