The fines - $10,000 for Encore and $20,000 each for MGM Springfield and Plainridge Park - are much less than the millions the venues have pulled in this year from in-person casino and sports gambling. The three cases stem back to basketball games in early February, only a handful of days after the launch of in-person sports betting at Encore Boston Harbor, MGM Springfield, and Plainridge Park Casinos. Gaming regulators fined the three casinos in Massachusetts with in-person sportsbooks a total of $50,000 Tuesday for illegally allowing patrons to place wagers earlier this year on sporting events involving in-state collegiate teams.