Texas horse and dog racetracks and their supporters have solid arguments that they should be allowed to conduct wagering on “historical racing,” a technology that displays races previously run at licensed racetracks, removes identifying markings but allows bettors to use official handicapping information before testing their luck/skill.The industry is united perhaps more solidly than it has ever been before. Leaders of every horse organization in Texas racing, every licensed racetrack in the state — including Lone Star Park in Grand Prairie — and the greyhound breeding industry signed a letter of support presented to the Texas Racing Commission before a hearing on Tuesday.With such strong arguments and such unity, it’s a shame the industry isn’t going after the full blessing of the Legislature instead of trying to push the change through the commission. You’d think they’d be proud and confident and wouldn’t want to look like they were going through the back door.It’s true that the racing folks have reason to be sensitive. They’ve been knocked around pretty much every time they’ve gone to the Legislature seeking new ways to make money — most notably when they’ve sought or considered seeking slot machines or casino gambling at racetracks.But this time they can make a good case. Historical racing terminals are not slot machines. They are electronic terminals, but the resemblance ends there.Bettors don’t just pull a handle and accept what happens. They bet on particular outcomes, just as they do in live racing.The industry is hurting and needs new sources of revenue. Success depends on how much the tracks can offer in purses to winning horses and dogs; the more they offer, the better the racing animals they can attract and the greater the crowds will be.Thoroughbred horse races in Texas offer daily average purses of $139,459, the industry says, compared to $352,235 in Kentucky and $347,796 in Arkansas, both of which permit wagering on historical racing.The industry is confident this change would turn around 10 years of declines in jobs, purses, live races and wagering.But apparently not confident enough to take it to the Legislature.