I can only talk about Canada, but in both Ontario and western Canada they scan your ticket and an audible sound is made if you are a winner (or loser). For both winners and non-winners, a receipt prints out and the clerk gives you both.

Additionally there is a self scan kiosk where you can check your ticket. And there's always publicly listed winning numbers.

However, I will add that often a clerk won't scan your ticket if it's not signed. Therefore, if you want to check your numbers without signing the ticket, your options are self scan, their official app, online numbers, newspapers etc. Lots of options.

No idea how the system works, but if the clerk is able to disable the scanner and manually press a hidden button that plays the audio of the losing sound, seems like a pretty easy system to break.

And print out an official lotto receipt on their official paper.... come on.

Who stays for their losing receipt?

Probably not many people do, but the point was made in regards to the comment that "a lot of people are cheated out of their winnings". I made the comment to simply point out that may have been the case in the future, but most modern lottery corporations have made efforts to eliminate that.

Or if the clerk scans a losing ticket of their own, from their pocket.

You have anything to back that story up? Even an online article?

Most lottery systems around the world will buzz a "winner" or "not a winner" sound and some flashy lights when you bring the ticket to a clerk. Try it in Germany, England and USA (places where I played lotto and witnessed it firsthand)

Sure. Here's an example from just a month or two ago:

http://wfla.com/2017/12/12/gulfport-and-st-pete-store-clerks...

(and yes, a lot of systems now have self-service terminals that one can use to check your own ticket, and cashier terminals that make audio, but fraud will always find a way.)

Even an online article?

Were you looking for a paper copy? I don't have your mailing address.