There's nothing inherently wrong with drum brakes. They are extremely simple, long-lasting, and reliable. The brake systems on most vehicles with rear drums are heavily biased to the front anyway, meaning the rears are largely supplemental...and for the parking brake.
I've replaced the rear brakes on my old Caravan twice in 20 years and over 265K miles. And that was largely preventive maintenance, not due to wear.
Vehicles with rear drums are so-equipped because that's all they require. Unless required - like you'd see on a high-performance vehicle - why add cost and complexity? Because it sounds neat?
Many of us grew up driving 60s and 70s Chevrolets with drums at all four corners - and lived to tell about it.