The survey would determine how many eggs people eat, both directly (omelettes) or indirectly (or as a component, as in cake):
* https://www.statista.com/statistics/183678/per-capita-consum...
And from there the BLS would know how many to put in the basket of goods it uses. Which they have listed in this table:
* https://www.bls.gov/news.release/cpi.t02.htm
And here's the data series for the price of eggs:
* https://data.bls.gov/timeseries/APU0000708111
* https://fred.stlouisfed.org/tags/series?t=bls%3Beggs
What people put in the the survey would indicate the the "importance of eggs" (in the average case).