Sliding tackles can often be sources of controversy, particularly when players being tackled fall down over the tackler's foot (or the ball stopped by the tackler's foot), and penalties, free kicks and cards are assessed (or are conspicuous by their absence).
Reckless means that the player has acted with complete disregard to the danger to, or consequences for, their opponent.
[1] The slide tackle is attractive to the defender because it allows them to cover a larger area of ground while attempting to dispossess an opponent.
It is often a "last-ditch" attempt to dispossess an opponent due to frequent misses and the difficulty of recovering in the event that the slide tackle fails to take the ball away.
After a slide tackle, the tackler is left sitting or lying on the ground with one leg extended.