Probably quite right, but governments always look at the dollar savings at the source, which is the pension they have to pay. If you stay in the country you are fully entitled to all the perks associated with being an Australian resident.
Totally agree with the freedom of movement policy, but that's long gone. There's no comparison of that with the payment of state pension. Anyone who qualifies for the pension gets it, and anyone who qualifies for portability gets it. Where people go wrong with this, is they believe they have "paid in" to a pension scheme (which they haven't) and are entitled to it (which they aren't). The bottom line is it's a welfare payment. Those with company or private superannuation are fully entitled to it. It's not means or asset tested, pensions are index-linked and best of all, after age 60 it is totally tax-free. And completely portable.
Yes, the state age pension is a welfare payment. It's paid from general taxation which includes unemployment, disability etc. Payment is based on individual needs. It's not a defined benefit the way, for example, the UK state pension
Unfortunately Australia does not have a contributory national pension system the way the UK does. In the UK, people do actually "pay in" to a National Insurance system which does guarantee a pension on reaching a certain age. Australia doesn't have this, but merely operates a social welfare system which really only benefits those who have comparatively little.
Actually no-one is being held captive. During covid anyone with a legitimate reason to leave Australia was totally allowed. I personally know a few people who were in and out several times. It was not much different to how Thailand was operating. Travel between different areas was restricted, and people coming in were subjected to quarantine.
Yes that's possibly part of the thinking too. A person being paid a welfare payment is probably expected to spend that money in the same economy. However, it is what it is, and it can be worked around at some inconvenience
Australia doesn't have a government "pension system". There is no contributory pension system except as provided by law through the employer. The government system is a welfare system designed only to help those who are in "need" of it, and have insufficient assets or means to support themselves. People who haven't worked a day in their lives and have nothing are entitled to it. So what you get from welfare is not "your money" as you suggest. Canada is probably different. In the early 1980's Australia started a compulsory superannuation system whereby individuals and their employers provided the funds for future retirement needs. I don't qualify for the state pension as I have a very lucrative superannuation pension. This is even though I paid taxes my whole life (however in Australia there is no connection between tax paid and state pension entitlement). My private pension is mine to do as I like, I have no restrictions as to where I live, and it is a defined benefit. I can start working again and my benefit is unaffected. What my nation "should" have and what it has got are two very different things. I was merely pointing out to the OP how and why the state pension works the way it does.