> There is no benefit to having people be able to draw the flag accurately. A flag has two purposes:
The purposes you mention are much more easily achieved by being simple to draw.
Yes, it is something "someone is arguing" but it's congruent with general design principles you will see in most domains.
> a Spaniard claim her flag was easy to draw. She meant that it's easy to draw if you don't bother to draw the coat of arms.
She's not exactly wrong. Many countries use variants of flags for different uses. In the case of Spain[0] the civil flag does not have the coat of arms.
For a similar case, see the flag of Germany[1], Austria[2], Peru[3], Finland[4], Italy[5], and need I go on?
I don't think you should be ashamed for not knowing, but it's worth recognizing how easy it is to miscommunicate because different inherent assumptions are being made. In your case it is unsurprising that there is this disagreement because she sees the civil flag commonly and you don't, so it seems like a cop-out to you while it is pretty reasonable for her. There's surprisingly (annoyingly) a lot of depth to seemingly simple things.
[0] https://en.wikipedia.org/wiki/Flag_of_Spain
[1] https://en.wikipedia.org/wiki/Flag_of_Germany
[2] https://en.wikipedia.org/wiki/Flag_of_Austria
[3] https://en.wikipedia.org/wiki/Flag_of_Peru
[4] https://en.wikipedia.org/wiki/Flag_of_Finland
[5] https://en.wikipedia.org/wiki/Flag_of_Italy