"you get treated like second class human beings and are forced to fight and prove you deserve something others were simply born with." isn't this effectively the situation with immigrating to any desirable country (and even some undesirable ones)?
Happened to travel internationally, either to see family for a week or for a conference in the 3 years between finishing your education and getting a chance at an H1B? Maybe they'll let you back in, maybe they won't, no one can say.
Happened to study and work here for over a decade, slaved away for an employer to convince them to sponsor your residency?, Employer screws up your green card application after pushing it off till the H1B limit, you get screwed and have to leave with zero recourse.
It's no wonder illegal immigration is such a big issue here, especially with sanctuary cities, you come and stay illegally and governments will bend over backwards to help you stay, you come here, get an advanced education and work hard to remain in legal status for a significant chunk of your life, supporting yourself financially and giving back to the country and you get kicked out for something that wasn't even your fault.
In comparison DMVs and even the IRS aren't renowned for being in the habit of completely wrecking someone's life's plans over the mood of one random person. There are pretty blatantly wrong things people have to do (and keep doing) for the DMV or IRS to have a similar impact on their lives.
Still, to answer your question, the difference is in the number of dealings an immigrant has to go through and the consequences if any of these goes badly. If you mess up your DMV meeting every 5 years, no big deal. You failed to update your address in your annual license renewal as an immigrant? That is a potential black mark that can get your green card denied and your life ruined.
Maybe it is the case for every country to treat immigrants like that. But when the US is built by immigrants, it should have an incentive to do better than that. Otherwise, why would people immigrate here instead of all the other "desirable" countries, or maybe just come back home? In such situations, sure, the US hasn't done wrong. It simply had done worse than it used to. And that can be a subjective sign of decline depending on how you look at it.