BUFF BOT LANE TOWER

Why the f**k does 90% of my tower disappear if I even dare to back once? Earlier today, I was playing Vayne against Caitlyn. Literally 1 minute in, my computer shuts down. I turn it on and get back into game maybe 2-3 minutes later, and LITERALLY 90% of it is dead. Hell, even if it's not dc; even if I get pushed out of lane and need to recall, I'll still lose half of it at best. Why isn't it like this in top and mid lane too? This is the reason the game snowballs so much. After their bot take our tower, they get mid and take theirs too. It's just way too unforgiving and makes it literally impossible to come back. At the very least, make it so I have a chance to defend it if I have to back.