I asked them if I show the laptops and the receipt for the import tax when I leave the country, will they refund the import tax.

Nope, that will not happen they told me.

If it was true that it was to avoid that I sell any of the laptops, it should also be possible to get the import taxes refunded upon leaving the country with the same laptops. But such is not the case :(

The obvious question here is, does Mexico in fact levy import taxes on incoming personal laptops, or were the airport people collecting a bribe?

Iirc, you're entitled to bring in a single laptop, above that, import taxes may apply. The issue is that "personal laptop" is not really something the customs has evidence of. They just see someone with multiple laptops, which could represent intent to sell.

In the interest of curiosity, everyone should read more about the situation - political, economic, etc. - of Mexico in order to understand the sincerity of a policy like import taxes on extra tourist laptops.

Links would be appreciated.

The US has a southern border crisis because nearly every country from Mexico to Chile is experiencing severe economic and social problems.