The deliverables are drastically different between different photographers as well. The wholesale cost difference between our upper-end album and the lower-end one is about 600%.
I don't remember the article to reference it here, but the current cost of weddings was started largely by the introduction of gift registries. It snowballed from there.
The wedding photographers have some clever ways to sell you more stuff too. Most of them want to retain the rights to the photos that you pay them to take, so they can sell prints to your guests or license them as stock art and stuff. I actually got into a shouting match with one photographer over that -- I insisted on treating the photos as works for hire under US copyright law. One guy had "his and her iPods" that he would load up with wedding pics at the end of the reception. The cost? $1000. Yeah, no thanks.
I won't go into your second paragraph, though, because that mostly boils down to a difference of opinion.
Obviously there are expenses that come out of the basic fees, but when I was doing this, the people I talked to at the lower end of the cost spectrum seemed to operate without some of the expenses that came up (ie, home studio, little/no advertising).
The point I was trying to make was, wedding photography is competitive but potentially lucrative if you can establish yourself, particularly in markets like SF.
I think there'd be a few people who get into wedding services expecting it to be lucrative and then find it a lot more difficult than they expect. I've mentioned on here before (check comments history) a client of mine who got married, noticed the huge prices, bought a wedding services business and then sold it within six months - more hassle than it was worth!
I'm saying that but my wedding photographer had just come out of college. We paid $750 for the photos and it was a pretty good deal, she had some shots taken during school, they were pretty good and that was all we needed to decide. I think we were her first customers of her new company. It was a risk but now days, every aunt and uncle comes with a digital camera.
I think they'll be OK with me saying this much: the data do not agree with your conclusion, for any sensible value of "liberal arts."
Now photography, that is another story. My research methodology totally missed it as a major choice, because the obvious occupation (photographer) doesn't require a degree. Looking at the BLS source data though, egads, $170k to become a photographer is a bad call economically. The median annual salary (note: for photographers at all stages of their career) is $19k. The overwhelming majority are part time only. If you give generous assumptions as to future income growth, the NPV of being a photographer is $410k.
That compares disfavorably with every degree I actually have in the data set. (Including, most relevantly to her situation, the associate's degree you need to become an X-ray technician, which you can get for less than $5,000. Spend another $10,000 on camera lenses, bam, you're an X-ray technician doing something she loves as a hobby.)