Because guarding the tomb is entirely symbolic, but it's taken very seriously, and maintaining high enough standards to put yourself out there for scrutiny like that is hard as hell. Put the discipline and dedication required on top of all that and it's very much a job worthy of respect, at least in my eyes

It’s a voluntary position and an honor. It’s a boring, painstaking job. You’re doing it to honor fallen comrades.

You should look into that position on wiki, it probably would give far more than any comments here. It's very demanding, important symbolically, and it's a huge honor for anyone to say they served it. It's at the level of the King's Guard in London, if maybe you're more familiar with that.

Mass effect had it right

“Stand in the ashes of a trillion dead souls and ask the ghosts if honor matters. The silence is your answer.”

It's all just a dog and pony show but there is still no reason to go there and be disrespectful.

more honourable than any other job

they didn't make that comparison

Odd question to ask the day after Armistice Day. But I'll give you the benefit of the doubt and bite.

Many western countries created a Tomb of the Unknown after WWI to honor the dead that never got counted or identified. This job is considered honorable because of the significance that it carries to the nation.

You gotta keep in mind that, back then, we didn't have a standing army, it was a draft or nothing, so it was untrained boys that got called up and an entire nation that rallied behind them. (This is also the reason the NRA exists, to be a club that teaches citizens how to properly and safely use firearms, not the lobbying monstrosity it has become today)

Its only in recent times, especially the Bush eras, that the homefront carried on as if nothing was different while a war was on. That's one reason they've been able to have forever wars, because it could fall into the backdrop of society behind Real World and the Kardashians so we would forget to give a fuck about what our troops were doing. (This is also why "Support the Troops" was more common 20 years ago, because it called back to a time when it meant something, even though we now know it means fuck all)

That wasnt how countries went to war back then. So because of the significance is why we allow that job to be considered honorable than most.