Wheel nuts were sometimes an issue back in the early 2000s and earlier, but it was generally with either cross-threading or midfielder teams fumbling – due, perhaps, to insufficient practise. Once the big teams demonstrated that sufficient practise could make a well-drilled team, the practise (pun intended) percolated down the field, reducing mistakes. Some teams at both ends of the field also found good ways of preventing cross-threading.
However, the combination of reduced stop time (to which LL Jehto alluded) and the increase in pit stops (to which Keith alluded) has reverted the situation. Since the two factors are independent of financial firepower, all teams are getting about equal effects from this.