The UK has added restriction after restriction to becoming a citizen and applying for a work visa in the UK over the past 15 years yet the numbers keep climbing higher and higher. The fact of the matter is once Abdul becomes a British citizen in the eyes of law it starts a cascade where 1 Paki deigned with citizenship suddenly burdens the state with an extra 8 or more within a year or two of becoming one.
I'm not sure if it occurs the same in America, but here's how it happens:
First, Abdul becomes Bri'ish after working 5 years and applies for citizenship — he passes the test and becomes a citizen.
Second, Abdul brings over his spouse via family visa, and if both of them (I.E. just him since she'll likely never work) earns over 18.6k a year (minimum wage at 40 hours a week gets you 22k+ a year btw) then you become a citizen in 5 years.
Third, Abdul brings over his parents through a family visa. If they're old enough and get any sort of long term care on the NHS (prescriptions for
anything) they then qualify easily for the ADR (adult dependent relative) visa, and then have indefinite right to stay and can claim pension credit and NHS care despite never paying a penny into it their entire lives; since Pakistan largely charges for healthcare and one of the perquisites is that you can't afford healthcare back home, you can already see how easy it is to get this.
Fourth, after Abdul's parents have the right to say via ADR, they're citizens in all but name and so can add 'children' (don't have to be under 1

as dependents here which automatically qualify them for a family visa. Alternatively if their parents moved here on a family visa, their subsequent visa will automatically be granted if they were living with their parents back in Pakistan (there's no way to prove this btw) and get added to the list as dependents.
Fifth, if Abdul's siblings have kids, then they can get added as dependents of the siblings and come over too. If the parents become 'settled' (lived here for more than 5 years on family or work visa) then they automatically become citizens)
Sixth, if the unsettled siblings have a child that is born here, once that child reaches the age of 10, they automatically qualify for citizenship too. Once this child is a citizen, any parent that might not be a citizen yet (maybe they come and go through a visitor visa) can apply and likely become a citizen.
And the clincher? The spouse can do what Abdul did but for her side of the family too.
Some of these visas I mentioned are temporary and require extensions, but they're typically just granted anyway and after a certain length of time you can just qualify for citizenship. A 'skilled worker' visa is something you can apply for if you work in a kebab shop too, which after 5 years you can become a citizen. Visitor visas also allow people to reside in the country legally for 6 months for the price of £127 (or $16

Once it's often the case they earn money under the table via Ubereats and Deliveroo that their sponsor or sponsor's wife filled the profile out for. A lot of them also open up shitty shops or takeaways since working for one still qualifies as work for the accompanying visa.
They've built an entire system here that facilitates the arrival of more of them, the ability for them to work under the table, etcetera. The
only thing slowing them down is the fact some of them cost money and some of them have minimum time requirements.