Bowling machines were popular, because back in the day a bowling alley was the best location an operator could hope for.
Bowling alleys lived and died off the Leagues, and back then parents brought their kids to the bowling alley with them. Trouble was, leagues were rather adult situations with smoking, drinking, swearing, etc., so they tossed the kids a few quarters and told them to go make themselves scarce. The money they fed onto the pinballs was still cheaper than hiring a babysitter, and it kept the little nippers occupied.
In my town the bowling alleys automatically got every new machine first, and I've heard that the two bowling alleys made more money for the operator than all the bars in town combined.