LG isn't the only one making three-SIM card phones anymore. The Samsung Galaxy Star Trios, which you can see above, is LG's triple-SIM handset that was just launched in Brazil. LG's Optimus L1 Tri, with three SIM slots, is also available in Brazil, meaning there must be high demand for these types of devices there.
Running Android 4.1 Jelly Bean, the Star Trios features a 3.14-inch QVGA (240 x 320) display, single-core 1GHz Snapdragon S1 processor, HSDPA, Wi-Fi 802.11b/g/n, 2MP rear camera, 512MB of RAM, 4GB of expandable internal memory, and a 1,300 mAh battery. The device is available from numerous Brazilian retailers, in either black or white, for around $165 – quite a steep price for what's a low-end device, beside the SIM slots.
source: Samsung Brazil
via: PhoneArena
“(…) meaning there must be high demand for these types of devices there(…)”.
You are right, people like to have more than one carrier chip over here. There is even feature phones with four chips over here.