For a long time the legal drinking age was 21 but the military draft was at 18, so in a number of States the drinking age was lowered to age 18 or 19 in the mid-1970s. Then young people started having an increased frequency of serious intoxication and drunken accidents, and alcohol was made much more accessible to high school students. Various colleges had huge problems with out of control drunken students including the University of Colorado. Then there was a Federal backlash against drinking in the 18 to 20 year-old age group, and now the drinking age is 21 again. In Ohio the citizens voted by a 6 to 4 margin in 1978 to raise the drinking age from 18 to 19 to reduce its access to high school students and just a few months later the Federal government forced Ohio's drinking age up to 21 by threatening the loss of Federal highway funds. Who cares what the citizens of any State think on some issues?
I don't know the age of Rhode Island's law, but 100 years ago children were often expected to be much more mature at an earlier age than in today's world. In the mid and late 1970s I was expected to work full time right out of high school and live on my own with little financial help from home by 18 or 19. At age 20 in 1978 I was making $9.31 an hour working at a big factory and sharing an apartment with a friend. These days the 18 to 20 year-old age group has 70% unemployment nationwide. 100 years ago it was not uncommon for 14 or 15 year-olds to work in underground mining in this country, and 200 years ago there was a job called "cabin boy" on large ships of that era where many the employees were even younger. So I would not find Rhode Island's law to be terribly unusual if it is at least 80-90 years old. It is a bit surprising that such a law wouldn't have been modernized yet. In Colorado's gold mining days bordellos were legal and were not made illegal until right about the same timeframe as Prohibition, likely by the same morals crowd that pushed outlawing alcohol too. I don't know if there was a set minimum age under Colorado's legal bordello law in the late 1800s/early 1900s or not, but my guess is that there was.
In northern Nevada and even in Pahrump, NV near Las Vegas, bordellos are still legal today, and there must be a State law in Nevada governing a minimum age of participation in the industry. My guess is that Nevada's law has been changed over time to exclude younger workers. It sounds like the majority of Rhode Island's population would support raising the minimum age for participation in the strip club business, and that may yet happen. The issue with strip club dancers being assaulted is not a new one or an issue confined to Rhode Island either. A change in the age law for professional dancing would only protect the age group excluded in any new law.
I've been to Rhode Island's ONLY truck stop, at Exit #3 off I-95, several times in my life, and have delivered loads of Breckenridge beer out of Colorado to a distributor in Providence too. I haven't frequented a gentleman's club in many years now, nor do I have the desire to search-out one of the Rhode Island holdouts either. Perhaps you could spearhead a drive to raise the participation age to 17 or 18 just by printing-up a bunch of flyers and nailing them to telephone poles if you feel strongly about this issue. Dont get caught doing it though or they will make you remove all of your flyers too. Late night in dark clothing used to make me nearly invisible when I was younger.
I would guess that the majority of us would find that the old law in Rhode Island needs to be modernized on this issue.
"We stay here, we die here. We've got to keep moving". Trucker Mark