It was not clear in your previous comment that "very closely related variant matching" included as well not so closely related variants like synonyms and related searches, given that you said it meant "plural to singular."
> Broad match is the default match type that all your keywords are assigned if you don't specify another match type (exact match, phrase match, or negative match). The Google AdWords system automatically runs your ads on relevant variations of your keywords, including synonyms, singular and plural forms, possible misspellings, stemmings (such as floor and flooring), related searches, and other relevant variations. To help deliver relevant matches, this match type may also take the customer's recent search activities into account.(https://support.google.com/adwords/answer/2497828)
Edit: The critique above may not be fair because your point seems to be that "broad match" is not the default setting (so you really think that the default shows only very closely related variants and not synonyms or related searches). However, if this is what you really meant then you seem to be wrong.