Just about everyone you listed was in the top 5 in terms of power at the time.
Zarbon was Frieza's second in command. And Recoome was the 2nd Strongest in the Ginyu Force. So during the Namekian Saga Vegeta fought against Number 1,2, and 4.
18 was just as powerful as 17, and they were only outpowered by Cell. Keep in mind Vegeta became strong enough to beat a Level 2 Imperfect Cell, and that was after he had an androids power stacked on top of his own. He only lost because he was arrogant and let Cell get to his Perfect Form. No one could even touch him aside from Goku/Gohan(Rage Mode)
All the Saiyans had trouble with 13, 14, and 15.
Broly? Really? You're using Broly? The guy who wtfsh*tstomped just about everyone before Goku saved the day?
Fat Buu and Kid Buu were both extremely powerful and outclassed just about everyone. It took SSJ3 Goku and Gotenks to even contend with them.
Same deal with Super 17. Goku had to get 18's help and use a super move just to take him down.
And Omega Shenron was literally the most powerful villain in DBZ and DBGT.
That's like bringing up how Superman got killed by Doomsday and hurt by Darkseid and had trouble with Shaggy Man, etc...
Yeah, but it's not completely constant and they're blinking in and out of sight while doing it. You seriously can't be comparing boxers against Saiyan Saga and above fighters.
Superman is practically undestructable, unless Vegeta finds kryptonite he is gonna be pulverized.
__________________ -Signature property of DeathKap- "... If fate is a millstone, then we are the grist. There is nothing we can do. So I wish for strength. If I cannot protect them from the wheel, then give me a strong blade, and enough strength... to shatter fate."
Any Vegeta besides the Vegeta from the first arc will lose.
[SPOILER - highlight to read]: Little known fact: The fur of the Saiyan tail contains small traces of brown kryptonite, which has the notable effect of giving Kryptonians an absolutely horrible case of the shits.