Why are southpaws so hard to defend against?

I recently discovered how hard difficulty it can be to defend some punches against southpaws. I recently had a moment in boxing when I fought a guy who was a southpaw. Now by no means do I have a problem with southpaws at all. My defense is pretty good against them actually. I usually pick them apart by finishing my combinations with jabs, using lateral movement, and slipping or ducking wide counters on the inside But the problem I noticed that on the inside it felt very confusing. I tried to throw my left hooks they would always get caught on his left hooks or my right hand could only be to hit certain targets like the middle of his gloves with a right uppercut. So in result I ended up tyeing the guy up every time he got close and ended up winning. But I felt bad because it felt like I was taking advantage of him I noticed this with the best fighters too. I remember back then when Pacquiao was alot younger when he drive into his opponents bubble he would back up in a straight line only to hit by counters. Now in most fights you see him youll usually see him either completely turn the guy around or tied up the guys arms when he tried to counter. I noticed Floyd Mayweather did this too as he noticed at some point in his career that trying to roll punches against a southpaw didn't work to well. You can noticed the changes in defense he used in fights like Robert Guerrrro compared to Demarcus Corley What Floyd learned from those tough rounds against a few southpaws early on in his career was how to take the jab away from his opponent. I noticed that against Judah & Corley, he tried using his hands or arms to defend the jab a lot, whether it was a catch or parry. Against Robert Guerrero he hardly used his hands to defend the jab, he almost always used his feet. A simple step back / pivot and lateral movement. As they couldn't get their jab going, they resorted to throwing risky shots which Floyd ultimately capitalized on and countered. Guerrero's punches were wild and Floyd hardly allowed Pacquiao to get into range. It's all down to angles. Even the very best, like Floyd, will feel uncomfortable trying to catch/roll/slip/parry shots from angles they aren't accustom to on the inside. Getting the feet tangled up doesn't help either. It's safer to stay out of range where you have more time to see the punches coming from the different angles (southpaw stance). This is exactly why Floyd kept Pacquiao out of range. He could see the shots coming and had plenty of time to adjust his feet and prevent Pacquiao from getting anything off.

everything is backwards with southpaws..if you are not used to fighting them it is weird.