For one thing, shopping at Dollar Tree is not an antisocial behavior that harms other people, so you do not need to justify it by saying you needed to do it. You are free to shop at Dollar Tree whether you "need" to or not if it pleases you to do so.
The equivalency you're trying to draw between shoplifting and shopping at Dollar Tree isn't there.
Clearly, anyone who believes “there is no ethical consumption under capitalism” would disagree. A fair number of the people who would readily acknowledge that there is ethical consumption under capitalism, and even those that see consumption under capitalism as presumptively-but-not-categorically-ethical would also disagree. [0]
[0] for some reasons they might, https://time.com/6273646/dollar-stores-osha-labor/
If you read an article about Dollar Tree and it makes you feel bad and you don’t want to shop there, that’s your prerogative.
For me, I’m not interested in being guilted into assuming ethical responsibility for the decisions of the Dollar Tree management. I presume they are adults of sound mind so the responsibility for their choices is theirs alone.
FWIW I can probably count on one hand the number of times in my life I’ve shopped at any dollar store so it’s a moot point.