[hulitu]

They look like propaganda posters from after WWII.

[quesera]

That is the design intent. They are modeled after WPA posters from the 1930s-40s.

"Propaganda" has negative connotations today, because it has been used as a manipulative tool. But that was not always the case.

WPA: https://en.wikipedia.org/wiki/Works_Progress_Administration

[Black101]

Fake news is the new propaganda...

[jaquers]

If by "look like", you mean they have bright-colored illustrations and text on them - that comparison would make sense.