I have no idea who "they" are.
Very often, the exterior drain tiles on existing structures are very costly or ineffective because of installation problems (patios, sidewalks, attached garages, steps and landscaping). If the basement is unfinished, it is a "piece of cake" to install interior drain tile at the level of the bottom of the footings, put in a sump and provide power and a means to pump out any water when required. An interior system also does a better job of reducing the upward hydrostatic force on the basement floor slab.
Obviously, both interior and exterior systems combined would be very cheap on new construction, but few contractors will include it as a standard of construction quality.