I didn't know about Starlabs but apparently THEY HAVE SHIPMENTS TO MEXICO YES!!!
regarding your question these are these major reasons:
for the most purists, the vendor should have a certificate from FSF saying that "it respects your freedom" a thing that almost no company have (at least that's what I saw in modern vendors)
in my case and other regions, it's way more probably you can get a Thinkpad easily and more cheap than one from those mentioned