The player who never turns is usually doing one of three things: receiving with no scan before the ball arrives (so they don't know if turning is safe), taking a first touch that stops the ball dead (making the turn a separate second action that's too slow), or genuinely having a defender close enough that turning is wrong (but not recognising when it is and isn't safe).
The scan-before-receipt habit
The turning habit starts before the ball arrives. Use the Half-Turn First Touch and Pass drill — the first touch is directional, meaning the player must already know which direction they're turning before the ball arrives. In 15 minutes, 40+ reps of the "decide then receive" pattern.
The directional touch drill
In a rondo, add the rule: after receiving, the player must play in a direction that's at least 90 degrees different from where the pass came from. This forces a directional first touch rather than a return pass in the same direction.
The press-reading skill
For players who genuinely can't read whether turning is safe: use the First Touch Under Opponent Pressure drill. The passive defender gives real information about pressing distance. Players learn to read "defender at 2 metres = can turn; defender at 0.5 metres = can't turn" through felt experience rather than instruction.
The coaching vocabulary
Give players two words: TURN (space to turn, do it) and HOLD (defender too close, lay off). Use these consistently in training until they become instinctive. These are the same words as GK communication — reinforce the vocabulary site-wide.