Obtaining a medical license is an entirely different process than being board certified in a specialty. A medical license is given by a state based on established criteria in that state. Usually it means at least one year of residency in the US or Canada, in some states there are a range of other rules or more years required. With that license, one can practice medicine. What exactly that means is way beyond the scope of this post, but it might include providing care for children in some states and settings.
Now, residencies are under the auspices of the ACGME (for allopathic ones). Although the ACGME works with the various specialty boards, including the ABP (Am Bd Ped), they are not the same. Furthermore, lots of folks complete non-pediatric residencies and "practice" medicine including caring for children. This includes family medicine docs and even at times internists who might be practicing. Furthermore, it is possible for physicians who complete fellowship training in the US (e.g. in a pedi specialty) but have not done a pediatric residency in the US to practice their specialty.
The ABP does not determine who can get a medical license, who can provide care for children, or what limits of practice exist for non-boarded physicians. They only determine who meets their standards for becoming board certified. For a long-time, board certification in pediatrics was "lifetime". You took the test and never did it again. I did that for both pedi and neo. I chose to voluntarily recertify in neo but keep my lifetime certification in pedi and not voluntarily recertify pedi as it isn't useful for my practice. Currently it is unnecessary for most time-limited certifiers in pedi/subspecialty to recertify general pediatrics if they intend to practice only specialty medicine.
Now then, here's where it gets hazy. There are lots of reasons why a physician providing medical care to children (lets leave surgery, derm, anesthesia, etc out of this) as a primary care doc or in a specialty might not be board certified in pediatrics or a pedi specialty. They include:
1. Just graduated from residency and haven't taken the boards yet
2. Took the boards and failed and are waiting to retake
3. Were trained internationally and are not eligible for boards in pedi in the US (Didn't do a US/Canadian residency) but did do a fellowship in the US and thus have an unlimited medical license.
4. Simply chose not to take the boards (often related to family reasons - having a baby at home, etc)
5. Did not do a pediatric residency (e.g. did family medicine, EM) but are seeing children.
6. Are training in or working in another area but moonlighting in an urgicare center, etc.
7. Time-limited certification has lapsed.
8. Rare special exceptions to practice rules for experts from other countries.
I'm sure there are more. A medical license allows all of these to care for children. Individual hospitals may choose not to give any or all of these practice rights there and a group may choose to hire or not hire these. Almost all hospitals/groups would hire several of these categories depending on many factors. Why? Well, it's obvious for #1 and honestly I think it's obvious for some of the others for most places. Other places might simply be short-handed and be willing to take someone who is adequately trained in their view but not certified for one of those reasons. Not much stops you from hanging out the shingle and practicing as long as you don't call yourself a "board-certified pediatrician" if you're not. Easy enough to check at
www.abp.org
Is this appropriate (probably your real question)?
In my mind, yes. It should be a goal for those who care for children to have the appropriate boards (which might include family medicine, etc) but it is not as simple as "no boards, no practice". Every situation has to be evaluated individually. There are great docs out there who fit into one of those categories and, for practical reasons, may never get boarded in any specialty.