How are product purchases supposed to work with crypto?

Awhile back, I spent 0.2 ETH for video cards at pcbitcoinshop.com . It did turn out to be a scam, and I'm ok with that as an experiment to understanding how all this works (or doesn't work) using a small order. And I'd like others to learn from this experience:

For instance, I made two orders. The second order was along the lines of "send your ETH to this address", and it was the same address as the first order. I wanted to cancel the first order, at which point I realized how would they know whether my ETH was for which order? (eventually I realized it didn't matter, because it was all a scam anyway)

The scam was sophisticated, including sending confirmation and tracking numbers after I had sent the ETH. But a couple weeks past, no order, tracking didn't work, and the website simply didn't exist anymore. Before the order, I did try to verify the vendor -- I saw references in forums where others had made orders, and it seemed the website had been around for awhile. Though it did stand out that it seemed the host was somewhere in Malaysia.

So here are some thoughts:

- If a vendor does charge say "0.2 ETH" for an item, how do this really work? Meaning, I can send 0.2 ETH -- but then there is going to be a transaction fee for sending the funds. So the vendor is going to end up with something like 0.19885534 or something. If I need to pay 0.2, how do I know apriori how much extra to add to account for the transaction fee? Or if the vendor just eats that fee, how would a vendor know it's not going to be a crazy fee at any point in time? (like if they got 0.15 of the 0.2 that I sent)? In fact, that's originally why I tried to cancel my first order (and they sent a nice e-mail that it had been canceled and all that) -- because I thought I hadn't paid enough, and I was about to go on travel for a few days without any e-mail, so I wasn't sure what to do. So before leaving on my trip, I actually sent payment again, and just sent a little extra thinking that "surely a legit vendor would just refund whatever appropriate if they had received an over payment."

- Once you send some crypto, it's like cash -- you've given it away, and the receiver can just disappear. I understand that's entirely the point here. But as proud as purist are about de-centralization, I still have comfort that I can call the credit card company and they're going to help me if I get frauded. Or if it's cash, I could engage police or a judge (if I can find the person and take them to court) if someone robbed from me, or didn't finish a job (like say I give $500 to a fellow for some backyard work and they just disappear 30 minutes later).

How is something like ETH going to address that? How are escrow services going to work? How do we defend against bad vendors (aside from requiring more positive reviews from others who took the risk before me)? Who do I go to, to raise an issue of the vendor sending me a defective, incorrect, or not at all product?

Wasn't the first credit card like in the 1950s? And it still took 30+ years for fairly mass adoption and usage confidence (CC's seemed more popular not until the 1980s, such as being in movies and pop culture; I remember movies of vendors cutting declined credit cards in half! I think that really happened in some cases). It will take time for issues like these to get addressed with crypto.

I can see ETH used like for a neighbor, to make a purchase like for some yard work or something they've sold (and we can both wait for the transaction has finished, and we can both quickly agree on any deviation due to the transaction fee at the time being sufficiently accounted for). But for online products and services? How is Amazon going to offer a return policy for things purchased with any crypto?