Originally Posted by
nth_utsera_sth_utsera
To londinense's point: it's not that foreigners aren't allowed to book cheaper fare buckets, LA cunningly runs an algorithm on its fares so that if the POS is outside Chile / Ecuador / Peru / Argentina it auto-prices to Y/B/H. You can easily overcome this by calling up a TA inside the POS and get them to issue for you. You'll need a reasonable command of Spanish though.
Unless you are travelling without check-in bags, your passport will be looked at when you check in and you will be 'fined' $178 if you have a ticket that's only for Peruvians. Also TAs in Lima will no longer issue these tickets for fear of incurring the wrath of LAN. There has been a lot of discussion on this issue at Trip Advisor.
The situation in Argentina is somewhat different, since the cheaper resident fares are government policy. In Peru it's only LAN operating this policy and it's being challenged. Many tourists in Peru opt to fly Star Peru, TACA or Peruvian, airlines that charge the same wherever you are from.