Currently traveling, and the savings are real. Although in this case it’s the opposite: travel eSIMs rates are about $80 for data for 30 days, whereas a cheap local prepaid SIM card is $8-16 (but with no eSIM option)
The service is called Holafly, it was advertised on the plane, and my travel mate bought it without hesitating (because of the convenience of an eSIM, even though they didn’t get a local number)
That's basically guaranteed to be overpriced. Anything prominently advertised means you're going to be paying for the advertising budget.
Also, it's "unlimited data", which probably makes it more expensive than it needs to be due to adverse selection. For instance it charges $50 for 15 days in europe, but on esimdb[1] you can easily find esims for just over $1/gb. It might still be worth it if you're using absurd amounts of data, but citing it as an example of esims being very expensive doesn't really make sense.
I don't know about europe but 40 to 80usd for 15GB for 30 days in Mexico is completely crazy when you can get a physical telcel sim card with 25GB and unlimited data for whatsapp and all major social medias, which means you can easily go for the smaller 10GB (15usd) or 7GB (10usd) choice if the most you will transfer is on social medias and whatsapp.
I found my google maps app for navigation and image translation via google lens/translator app ate up a ton of my data. I had to turn off off a setting or two to reduce the maps data.