DigitalGhost

Wow and I thought I had it rough the last time I lived in Toronto because there was no mail delivered on Saturdays.

Vulcanoid

Reducing numbers of people being turned around at the airport. Assuming people answer honestly, anyone who's ineligible to enter the country (eg criminal) gets refused at that stage, so can't even try to get there, people with exclusion orders can't chance it because they can't get on the plane, etc meaning those of us who do qualify (or, did, for those of us who became PRs) have shorter queues and are more likely to be let in on arrival, as much of the screening has already been done.

If people lie and travel anyway, there's a second chance to be caught, by the CBSA person, depending on how closely they examine people (and anyone getting through them both now probably would have before anyway).

Former Lancastrian

It stops PR's without valid PR cards travelling back to Canada by a Commercial carrier (plane, bus, ferry or train) without a valid PR card and forces visitors to apply for one before arriving much like the US ESTA and the Australian eTA.

It also helps with those who have criminal records either telling the truth on the application or lying and if discovered on entry with the eTA they can be refused entry and be sent back home or not being granted an eTA.
Note only VISA exempt countries require eTA and those who need a VISA require to apply for a VISA and if granted automatically get eTA attached to the VISA.

DigitalGhost

I understand what you're saying but if it's based on the ESTA model then in all likelihood most applications will be auto-approved as long as the applicant gives the 'correct' answers to the questions on the form and their details don't appear on any of the red flag lists that it checks.

In reality those systems seem like a money spinner and more of a way for border officials to reduce their interaction with physical paperwork than anything else. I'd be surprised if they actually made things any easier faster for honest passengers and in fact all evidence seems to suggest that they don't.

The queues in Toronto have never been all that bad either from my experience as long as you're cleared by front-line CBSA and aren't referred to secondary immigration or customs. They seem to move much faster than the lines at the UK border at least and are a world apart from the queues that people have come to expect in America.