It definitely wasn't at thing when I was in school, but maybe it simply hadn't reached there yet. I learned of that weirdness when I was already in secondary school, but it was a thing for a long time.

Iirc, it's been........a long time, we had a huge chart with the pictures you mentioned and we had a Fibel (to read) with single syllables and short sentences and we learned spelling by writing out each new word in a Kladde, that had to be prepared by the parents before the start of first grade with sections for each letter, like a dictionary. And then we had to write them down as, I think, "(das) Haus".

As languages where written and spoken match, German is still one of the easier ones. If only the grammar (and, admittedly, the genders) were easier....