the idea of examining the first tower statistic as a way to say that dying once in lane leads to a loss seems simplistic for a couple of reasons.
first, losing first tower is an indicator of a losing game, and a correlation, but not necessarily a causative factor of losing the game.
It's like saying, 70% of runners in 1st place for the first third of a marathon finish in 1st place. Well, if you heard that statistic, or a similar one, you would think, oh, of course, because they were already in the lead, it makes sense that they would end in the lead.
Similarly, If you are losing the first tower, that is usually because your team is behind somewhere on the map, and the enemy team has the wiggle room to send more than one person to shove down your tower, which means as a team you are 1) behind the enemy team in terms of kills/cs or 2) behind the enemy team in terms of map/objective awareness or just general teamwork. Your likelihood of winning the game was probably decided before you lost your tower or died once in lane.
secondly, as many players in this chat have mentioned,first towers are taken for a multitude of reasons, not just because of dying once in lane. improper backing, organized 4 man ganks/pushes/rotations, or just sloppy roaming can lead to your tower being taken.