While some have complained about how Boomerang is normally only available on relatively-high-tier satellite and digital cable packages, it should be noted that Boomerang is funded solely by subscription costs; this is why it airs no outside advertising.
Notably, Boomerang still uses Cartoon Network's classic "checkerboard" logo as part of its own logo; this is perhaps to keep the "classic" feel that Boomerang is meant to evoke alive.