As an R34 (remora) Col. Inoue leads mecha into battle. She does this without the benefit of a mecha of her own, instead relying on her own feet and a high power rifle.
The 228th Mountain Lion battalion faced a situation not entirely unlike General Custer some 500 years before. Like Custer's men, the 228th was almost completely destroyed, despite their laser cannons and drop ships.
A common mistake when writing adventures set in deserts is to assume that the climate is too ferociously hot to wear armor. Historically, most battles in deserts involved troops dressed in protective armor. Although they would have been miserable during the hottest part of the day or the hottest part of the year, desert weather isn't intolerably hot 24/7.