Pretty common for a place to say package is shipped when UPS has no data on it.
Clearly this is done so I can be charged for it 
From what I can tell, I sometimes get that notification when an order has been boxed, labeled and is waiting for the UPS pickup at the end of the day. (Since it’s not yet in UPS’s hands, they have no data on it yet.)
I’m always happy to criticize vendors or shippers when it’s justified, but I can’t agree with you here. Suppose I bought something from you, and sent you a credit card number. At the point that you had it boxed, labeled, and sitting out on the front porch waiting for courier pickup, or maybe dropped in a mailbox waiting for postal pickup, would you not have charged the CC and verified payment?
There is an additional problem here, which is also not the fault of the vendor, in that it takes some shippers 24 hours or more to record the tracking number on their system even after it’s been picked up. This tends to be particularly bad with postal services.
Exactly. It’s very common for me to get an email from various online vendors, with “Your order has shipped”, but it seems to be an automated email that is generated/triggered when the vendor’s shipping department generates a package ID number using the software of whatever shipping service they are using (USPS, UPS, etc.)
The emails almost invariably say, “It may take up to 24 hours for the shipment to show up in the shipping company’s system.” And, what it seems is that there is no information in the USPS/UPS/whatever system up until the package is actually picked up and scanned by the courier.
So, “Your Order Has Shipped” as a title on those emails is, yeah, a little deceptive. But, I don’t see it as the vendor trying to, as the OP suggests, “charge me for it.” It’s just a quirk of the way shipping companies work.
You have ordered something and know that you will have to pay for it. Why does it matter if they put the charge on your CC today, tomorrow or the next day?
Credit cards are billed monthly, so there can be anything up to 56 days free credit if you time the purchase right.
Certainly there would be an issue if I ordered it, they had none in stock, they knew it’d be at least 2 weeks / months / years before they would have any in stock, and they charged my CC today anyhow. That’s the problem with the “You know you’ll be paying for it eventually, so why not now?” argument. “Eventually” can be a long time.
At least in the US there are some regulatory and legal safeguards about “How close to being physically shipped is close enough to bill for?” I’m not conversant enough in the details to explain them, but they do exist.
As @kenobi_65 wisely says, most of the emails claiming the goods have shipped really mean “The seller / shipper has prepared the paperwork (computerwork?) if not yet the physical package. So your order is now in process for eventual physical picking, packing, courier pick-up, and later delivery.” Which distinction is disclosed cagily in the fine print, not in the email subject line.
I have to suspect that at least some of the rush by the seller to send that email is to prevent impatient buyers from thinking this is taking too long, then ordering the same item from somebody else, then trying to cancel this first order. By sending out the “It’s on its way!” email a bit prematurely, they’re also saying “It’s now too late to cancel this order without at least some cost and hassle on the buyer’s end. So don’t do that.”
they slap a label and charge you. Then it’s up to ups or USPS or fedex to do the rest
And? What’s the issue? Are you not getting your item?
When I used to give customers the choice between UPS and FedEx, I noticed that shipment notifications for UPS (and USPS) went out as soon as a label was produced. The FedEx notifications weren’t sent until I either printed a manifest for the driver or he scanned the label.