The shufflers in use at all legal casinos, Indian or otherwise, do not determine nor control which cards are dealt. Similar to the random number generators that run slot and video poker machines, automatic shufflers are tested and must conform to specified levels of randomness. Beyond that, the shufflers also speed up play and help prevent cheating (many of the "carnival" games like Let It Ride use automatic shufflers specifically to prevent potential control by dealers that might harm players), but influencing the outcome of the game is not part of their function.
As to your feeling that the games are tighter, that may be due to the farily recent introduction of the 3-card bonus bet. This is a third bet you can make in addition to the game's base bet (3.51% house edge with optimal play) and the progressive side bet (typically a 25%+ house edge). The problem is that the 3-card bonus bet with its most common pay schedule carries a casino edge of about 7%, so making it hand after hand, even for low stakes, will have a significant negative influence on your chip stack. Most players make all three bets every hand, and while that may produce a few exhilarating wins when a good hand does materialize, it's the worst way possible to play. If you play Let It Ride, it's best to stick with the base bet only.
