I'm sorry, there is no way lots of hygienists could have easily gotten into dental school. Your wife sounds like an extreme exception to the rule. Most hygienists go to community or technical school for 2 year programs (not 4). Only in Utah where thousands of dental assistants (working for the insane number of dentists there) want to upgrade to hygiene is the competition this stiff.
This is a lie we all love to tell ourselves. We look at someone who is more "successful" and say we could have done it. If that were true, we would have a quiet confidence instead of a prima donna, chip on my shoulder attitude.
We are all part of a team and each part is important. But, in the Northeast area most hygienists have two year associate degrees. Many do take pre-reqs on a part time basis before settling into a dental hygiene program often at community college. Most states have community colleges that are inexpensive to attend, unlike dental schools where even some state schools are not cheap. Whether a hygienist has a four year degree or two year degree makes no difference to me as an employer. All I am interested in is do they have a license, what kind of experience they have and what hours are they available. Considering the length of their education, dental hygienists and even dental assistants with an x-ray license, some who have attended a nine-month community college dental assisting program and some with experience only, earn a very good hourly wage.
Dental Front Desk $15+/hr + benefits (usually on the job training)
Dental Assistants $15-20+/hr + benefits. (education minimum 0-9 months)
Dental Hygienists $38+/hr + benefits (education minimum 2 years/18 months)
Dentists, employee, about $100,000+/yr + benefits, about $50+/hr ~many have considerable dental educational debt. (education minimum 8 years/81 months total, college 36 months, dental school 45 months)
Dentists, self employed as per ADA $180,000 about $100+/hr ~ many with considerable dental education debt and practice debt. (education minimum same for employee dentist - 8 years/ 81 months)
In today's market many DA's, DH and employee dentists are afforded a lot of opportunity have a flexible work schedule. Any DA's and DH's that are pining to go to dental school, nobody is stopping them. It's a choice they have to make. Choices are good.