McCarran is a slot route, owned by Michael Gaughan of South Point, so it's much like the gaming scenario you find in gas stations and supermarkets, operated under a "restricted" slots-only license. To offer table games, a suitably senior employee of the airport, or an outside-contracted third-party operator, would need an unrestricted gaming license, which is a far more complex regulatory proposition (see QoD Archives 8/7/15). Among the applicable logistical considerations, surveillance would have to become considerably more intricate, including the installation of color cameras – required by Nevada law – to make out the denominations of chips and plaques at table games.
According to the Nevada Gaming Control Board’s Chris Moyle, "there’s a different level of burden," including investigation fees (paid up front) and a full background investigation for the would-be licensee (again, see previous QoD cited above). As Moyle points out, the current McCarran license is likely conditional on the gaming being of a slots-only variety, although it's evidently more liberal than the standard "restricted license" that a video poker bar or gas station might have, since the number of slot machines at McCarran (1,298) far exceeds the 15 allowed under such a license.
Some other considerations: If a machine sits idle, it's only costing you the price of its electricity and a share of the wages of the skeleton slot staff on duty, whereas table games would need available dealers, paid by the hour, regardless of whether any passengers sat down to play.
Chris Jones, spokesman for the Clark County Department of Aviation, responded to your question bluntly, saying, "The airport’s limited gaming license does not allow for table games, just a slot concession." One casino that does offer table games – if you feel like a long trip – is Schipol Airport, in the Netherlands, where Holland Casino offers blackjack and "American" (i.e., double-zero) roulette, in addition to slots, and even a set of online tutorials (sample here) for the novice punter killing time before their flight.
