You are right, I stand corrected. It's been about 10 years since I last did the math and it's changed dramatically since then.
I'm sure it varies by region, but my grubhub app and the 12 pack of tacos (hard or soft) is $24.99 here so about the same as the $2.19 you found.
I had perplexity pro figure out the cost of purchasing the ingredients for comparable homemade tacos. With great value (Walmart store brand) ingredients it came to $20.04. $6.49 of that would be "left over" ingredients you don't use (mostly half a pound of beef you could use for something else later).
So you save $0.96 cents per taco by doing all the work yourself and using generic ingredients. Plus you get an extra half pound of beef for later.
So if your time is worth less than $12/hr it's a net gain.
I'm assuming it takes you only half an hour to travel, shop, and bring home the ingredients then half an hour to cook. If you live further away, factor in gas etc, the time it takes to do dishes, or are a slower cook then the break-even might come out closer to $6-$7/hr.