That is not the way charts work. This is not a horse race, where there is only one winner.
"Physical" would have sold just as many units, as it a different genre with different consumers. A Foreigner song might also have done as well or better... or not.
Remember, there are weeks where the #1 song sold vastly fewer unit than in a different week when there were more strong songs. That is why the year-end charts were based on sales often showed a song that spent weeks at #1 in a slow sales period ended the year outside the top 30 or 40 songs; its total sales just did not compare well with other songs.
This is yet another reason why radio stations research to find out what songs people want to hear today. The ancient statistics are almost meaningless
It is totally personal, as the meaning of #1 in sales can be vastly different from one week to another.
And, besides, songs don't "deserve" a particular sales ranking. There are plenty of songs that were huge radio hits that did very well in the kinds of research prevalent in any particular era but which did not sell well. In radio, we called them "turntable hits" and they were songs people loved to hear but which they never felt a need to buy.