Midland heavily marketed the GPX1000 as GMRS / FRS radios. They have non-removable antennas and are not repeater capable. I suspect they want to attract customers who primarily are interested in using simplex GMRS, like on a family farm, with the ease, familiarity and ability to do FRS.
They often sell these handhelds in combo packs with their micro-mobile units, which are fully repeater capable. Like I said, it must come down to marketing because they have been selling these combo packs for a long time and they seem to have attracted a large customer base. But hey what do I know, I am not a marketing pro.