The bittersweet un-bitter

Why are none of our back-yard vegetables as bitter tasting as store-bought, mass-produced vegetables? 

I'm asking about you.  A white onion I harvested two days ago. 

This is the biggest un-answered question that we have after three growing seasons.  There's a very clear difference in the taste quality, and it seems to persist across every species and variant. 

•  Is it because mass-produced vegetables lose so much freshness by the time they get to mainstream grocery store shelves?
• Is it because they are fed chemical fertilizers rather than being grown in naturalized conditions?
• Is it because they retain chemical pesticide residues that are affecting the taste?
• Does the handling and processing impart a taste?
• Some other reason?
• Some combination of the above?

 I don't know the answers.  I do know that I have a snowball's chance in hell of getting my husband to eat store-bought vegetables for that reason - because they are often so bitter-tasting.  I never noticed the extent of it until he pointed it out to me, and until we had this home-grown contrast to compare with.

Anyway, in transitioning from bitter to bittersweet, Tuesday was Onion Harvest Day and I'm always a little bit bummed about that because it becomes like the vegetable version of empty nest syndrome.

I grew three cultivars this year - red, white, and yellow (Texas 1015).  But one should not get emotionally attached to one's onion crop, because its days in the sun are strictly limited. 

It pains me to liberate them from the ground, but when onion tops start falling over like this, it's time to remove them no matter what size they've attained.  Otherwise, the bulbs will go into decline, and the bulb is the un-bitter part that you want to cook.  And maybe incorporate into many dishes than can be frozen and enjoyed for months to come. 

Moreso than other vegetables, onions seem to develop their own individual personalities or something. 

Muppet-like.  One of each variant with mop-top roots. 

The harvest this year is not nearly as large as it will be next year.  This I hereby resolve. 

Yeah, I'm that quintessential crazy old lady down the street who talks to her plants.  Maybe that's why they're not bitter.