Maremia asked: Why would Britain deliberately discriminate against British citizens?
The answer is: It doesn’t. It is the absolute opposite. It is allowing dual citizens with a British passport ease of passage and a right to enter the UK that a foreign national travelling on an ETA simply does not have.
I am repeating myself yet again because I suspect some do not read a thread, get a fixed and incorrect notion about something about which they become indigant and would rather be indignant than listen to reason.
An ETA is an Electronic Travel Authorisation. It is not, repeat not permission to enter the UK. An application for an ETA requires undergoing a pre-travel check which, if you pass it, means you will be granted an ETA valid for two years. This allows the carrier to let you board the plane, boat or train. It is not a guarantee that when you arrive in the UK, you will be allowed in. You will still be subject to immigration control and questioning by Border Force officers upon arrival.
A British passport, other than in very exceptional circumstances, allows the holder to enter and remain the UK, exempt from immigration controls.
Arriving in the UK on a foreign passport having travelled with an ETA, you may be granted temporary visitor status usually for up to six months. If you are a British citizen you cannot by law have visitor status as you already have right of abode.
Posit this situation. You have dual Australian/British citizenship and reside in Australia with family in the UK. A emergency arises and you need to travel to the UK urgently.
If you have a British passport, you can arrange a flight and travel immediately. The passport is your authorisation to travel.
If you do not have a British passport, you cannot apply for an ETA - as explained. Your only option will be to try for an Emergency Travel Document (ETD) cost £125, valid for one trip only. An ETD may be issued, typically to attend the funeral of a close relative or in cases of serious illness/death within the immediate family. You can use that with your Australian passport but, like the ETA, it is still only an authorisation to travel. Holders will still be subject to immigration control and questioning by Border Force officers upon arrival. The ETD must be surrendered to authorities at the border.
Look. If someone left the UK years ago, has no family or friends in the UK and is unlikely to want or need to travel to the UK in the next ten years, then why buy a British passport? But if there is the possibility of a need to travel to the UK, then buy a passport. It costs £143 including courier charges, valid for ten years. It really isn’t that much money to have the peace of mind that if someone in the UK might need you over the next ten years, then you can travel immediately and know that you will be allowed in.
Heathrow is the sixth busiest airport in the world with about 85 million travellers passing through each year. A plane lands or takes off roughly every 45 seconds during busy periods. Around 80% of incoming flights from Australia come into Heathrow. At busy times, immigration controls may take a couple of hours to get through meaning you might miss pre-paid travel connections. You would avoid this if you have a British passport.
In a time-critical situation why would want to risk that?
On British citizenship by descent. It usually passes down just one generation - single descent. You will automatically be a British citizen by descent if you were born outside the UK and at the time of your birth, one of your parents was a British citizen otherwise than by descent. A child born in Australia with one British parent and one Australian parent will have dual citizenship - Australian by birth and British by descent.
Someone with dual Australian/British citizenship is not having to fork out for nothing if they have no intention of travelling to the UK. If they do want to travel to the UK they need a British passport to guarantee them entry. It really is very simple.
If someone is allowed into the UK having travelled here on a foreign passport plus ETA they are restrcted on what they can do here. For example, they cannot do paid or unpaid work for a UK company or as a self-employed person, unless they are doing a permitted paid engagement or event or work on the Creative Worker visa concession.
Lets say someone does come to the UK for six months and runs out of money. If they had come on a British passport they would, legally, be allowed to work to earn some.
www.gov.uk/eta/what-you-can-cannot-do