I wonder why? Hmmm . . . actually, the article does a decent job explaining the obvious reason why there is such little interest in geriatrics. Every single incentive is geared against primary care and geriatrics:

Reimbursement drives doctors’ compensation. Gastroenterology, for instance, became more lucrative – and popular – once Medicare, which sets the standard for most other health insurance, began paying for screening colonoscopies. Geriatricians joke that they are waiting for the invention of a geriscope, so that they too can bill for procedures.

Meanwhile, much of what they do – communicating with family members, discouraging unnecessary tests – is time consuming but not reimbursed.