Ohio used to be like that. All the big fireworks stands were at the foot of the bridges leading to KY and WV. Of course that worked both ways, all the discount cigarette stores were located at opposite end of the same bridges.
Yes, MD has low liquor taxes (and they used to be substantially lower), and a lot of liquor stores right on the state lines, especially PA.
I recall a humorous story from many years ago, PA put a state trooper in the parking lot of a MD liquor store, who radioed the tags of PA cars to a group of troopers waiting across the state line. The irate store owner called the MD state police, who promptly escorted the PA trooper back to his state.
I recall some MD cops used to do the same thing in DC, which had (has? I don't play with fireworks because I prefer counting base ten) lax fireworks laws, to catch people buying stuff.
When vacationed at the Outer Banks each summer around the 4th, there would always be people setting off all sorts of fireworks. And I don't mean bottle rockets, I mean the real stuff. Just about every year you would read a story in the paper about some idiot setting the house on fire. And of course it wasn't their house, but the place they were renting for the week. There were also a few people setting the place on fire because they decided to run the gas grill UNDER the cottage, because it was raining.