1) I highly recommend your friend start doing this leg work themselves. You mentioned earlier in the thread about you contacting TAMU. At this point, your friend is completely capable of posting here, doing her own research into schools, etc.
2) Being a parent is not a substitute for upper division science courses. Vet school and being a vet are infinitely easier than being a mom. Nothing has been more difficult in my life. This gets its own point just due to the absurdity of a 21 year old whom I assume is not a parent making this comparison.
3) In general, this point:
1) Are you disciplined? 2) Are you committed? 3) Are you invested?
Is true for succeeding in a professional program. However, this generalization:
Upper division science courses are an easy proxy to these questions, but almost anything else could serve just as well (industry experience, being a parent, deep ideological drive, personal ambition etc.)
Is not. This is because of the vastly different requirements each of these take to be successful compared to the details of professional school. While being a mom is the hardest thing I've ever done, I am also a much better mom than I ever was a vet student. Not because my dedication, discipline, or commitment (redundant?) are any less. It's because the skill sets are different at their cores. I'm a better vet than I ever was a student because being a doctor and being a student doctor are two completely different things. Which leads to....
4) Nearly everyone who has replied to this thread are doctors, graduated veterinarians who have all played this game, got the t-shirts, and now spend time on this forum to share our wisdom of experience. We already know the effects and influences of upper division courses because we, like you, have taken them. However, unlike you, we have completed our professional programs. Some who have replied are PhD/DVMs and some are board certified specialists as well. And while it may feel like X class has zero bearing on being a student doctor or a doctor, they're a prerequisite for a reason (which you pointed out yourself). And that reason (besides those classes laying the groundwork for more complicated or indepth information) are to *teach* the dedication. The reason these are weed out courses is not because the information is difficult in general; it's because the soft skills they teach have a steep learning curve. And while your friend in particular may have those skills in her current field, those skills are not 100% transferable from one profession to another in all people. She will have the learning curve. How steep it is depends on her as a person. Age and experience in one are don't necessarily automatically equate skill in another.
5) I am that person who struggled in upper division courses, depending on the class (F in o chem 1 and a D in dev bio, plenty of Cs too), who winged it first year of vet school. And I failed out due to academics. My level of dedication was not any less than any of my friends, and no one at work believes me when I tell them I ended last in my class when I repeated. My point here is that "figuring it out later" is a bad plan. I missed a year of graduated doctor salary, paid for another year of school, and had to repeat subjects that I hated. The consequences of not setting ones self up for success early can be devastating. I'm fortunate to have attended a school where it's easy to appeal and repeat; there are some vet schools set up where you essentially cannot repeat and are permanently dismissed.