> Roman slaves were still slaves in that they could be raped freely by their masters

Nope. Only if so specified in the contract (of course, some slaves were explicitly hired for sexual services, just like today some people are hired for sexual services, from porn production to "hospitality services"). Also I do believe that rape was never covered, although sexual services might indeed be the expected "work" that the slave was contracted for, certainly.

Again, this is not really different for today. Would you say a porn actor/actress is "raped" ? Because in some ways you could say that their boss has them raped. How about people hired into brothels (and paid), who don't even know who they agree to have sex with when hired ?

> kids could be sold at will by the owner

Nope. Although there is some confusion. Kids were generally expected to help with their parents until a certain age, at which age they were free men/women. At that point, they could enter into a slavery contract (paid, was one of the conditions).

Generally there were various protections in slave contracts, against, for instance, large differences in job function. If an owner violated those, a slave could have the contract reviewed and gain his/her freedom.

It's not that different from the position of employee today. You can be "sold" in the sense that anyone can buy their way into becoming your boss (assuming your current boss agrees on the price, just like back then), and you cannot just immediately leave for just that.

> Slaves did not have any kind of legal rights.

Yes they did. The fundamental right any slave had was to ask for a review of their status, and whether the contract was upheld. Any and all slaves, even convicted slaves, had that right. There were various other rights that most slaves had, and generally the contracts specified extra rights. And, as I said, most slaves, especially in Rome, were not "fulltime" slaves. On remote farms, it was of customary for slaves to stay on the owner's property, for obvious reasons.

> some was able to save up buy their freedom if the owner allowed it

Roman slaves were always freed after a given amount of time. Granted, the state kept extending that time, but it was limited even at the very end (I believe to 10y for private owners, 20y for the state).

Even state slaves had "side jobs". For instance, most gladiators had a funny side income, and the state actually allowed and helped them with that. They would perform sexual services for any woman willing to pay for those (and apparently they commanded a very high price) on their off days. (note there were female gladiators too, even though not many, and yes they did the same. I believe one of the texts even points out that most of their customers were also female, and yes, any gladiator could refuse to do this, even though that was not a good way to make yourself popular).

Gladiator contracts are some of the known contracts, for instance. There were provisions that if you were killed (few non-convicted gladiators were, incidentally) the state would provide for your family or parents. You were allowed to have the above-mentioned side job, and you agreed to allow the Praetorian guard and 2 other military organizations to hire you if they wanted to, but you were allowed to limit your work there to, I believe 2 years or so (again, it is written that this is how they recruited officers, so essentially no-one ever left, though quite a few were killed along with the person they were protecting. BTW quite a few means a few dozen over 3 centuries).

> killed in gruesome ways like with crucifixion

Nope, although the state famously did that en masse to slaves (and some free men and women) in Spartacus' slave revolt, and on a smaller scale after that. I'm not saying that was OK, but I do hope you see that those were the state exercising punitive legal action on criminals, and not owners just doing that to their slaves for fun (like actually happened in the Ottoman empire, for example, killing/hunting slaves for fun)

> I wouldn't call this "extremely progressive".

Extremely progressive relates to what personal (non-criminal even) actions would get you banned out of polite society, or worse. In that regard, Rome was extremely progressive.

Senators in Rome were famous for just how far they went with this. Apparently in the Senate throwing a birthday party for someone else, and inviting 250+ prostitutes was, aside from the shear number of prostitutes, not a rare occurrence in the last years of the republic. Likewise having male-male, or female-female relationships, even with prostitutes was likely to improve rather than detract from your social status.

I understand that that doesn't mean doing this was free.

Let's say Trump, or Obama, or Clinton if you like, did the same. Let's say they all get together (spouses and children included), hire every prostitute on the west coast, and make a night of it, including gay and lesbian relations with prostitutes and guests, then brag about it in congress. Do you think society would understand ? Even the French, who seem to tolerate the president having a mistress, would kick out any politician, or anyone else, for that.

That's what I mean by progressive.