Not at all, look at the tooltips to see what’s going on. For example in the 90s, standard safety means driver’s airbag only, advanced safety means driver and passenger airbag. I have not seen less than two airbags on the vast majority of 90s cars, especially in the latter half of the decade.
So yes, it is realistic based on the game mechanics.
Unrelated, but I’ve edited the brief to state that the 20% commission fee is automatically added by the spreadsheet. Seems that wasn’t clear.