The success rate is around 70% because this government and the last one don’t have a clear plan, and they’re effectively waving them through in order to get people out of the system and free up capacity.
Which in turn provides absolutely zero deterrent to people making the crossings in the first place. Why would anyone apply for asylum before making the crossing when you have a roughly 70% chance of getting what you want if you can make it to the UK and convince people that you come from a particular country?
But equally, taking fucking ages attracts people too. People talk about asylum, but the other route is the trafficking claim. This is common with claimants from countries where there is no obvious grounds for refugee status, like Vietnam. Instead, you can claim to be a victim of trafficking, and while it's generally a less reliable way to be able to stay permanently, it does offer a route to getting dodgy work.
How it works is that you make your claim, for example, saying that you got into debt with a gang and they trafficked you to the UK to pay it off. They then have a 'reasonable grounds' decision, which is an extremely low-threshold check to say that there
may be a risk that the person was trafficked, and it has an 88% acceptance rate. The target for this is 5 days, but in reality, even this can take months. They then have to wait for the 'conclusive grounds' check, which is the higher threshold and more in-depth check. The target is 45 days, but in reality, it takes a year to 18 months on average. 54% are then recognised as having 'conclusive grounds,' but only 4 to 7% of those applying are actually granted leave to remain after this.
So why would you bother going through all that when you only have a 4% chance of being able to stay? Well the answer is that it takes so long that the amount of money you can make in the illegal economy in that time makes it worth it, and certain nationalities have a well-established network of this dodgy work (Vietnamese-run weed farms, for example). If people were processed in 45 days and 96% were returned home within that time, do you really think anyone would be paying thousands of dollars and risking their lives for a month of income? Of course not. But 18 months while they wait for a decision? Yeah, that's definitely worth it when you come from a country where a normal job is paying $300 a month.
And like everything else in the UK these days, you also have to think about who benefits from ridiculous inefficiencies. And yet again, it's presented as our tax money going to foreign scroungers, when in reality, the vast majority of that money is ending up in the coffers of private landlords, hotel owners, and other service providers who just happened to donate to the Tory party. It's amazing how a few friends in government can turn your hotel with 2.1 stars on Google reviews into a massive cash cow, isn't it? No-one's staying their by choice? No problem. Just phone up your mate at the foreign office and offer your services.