We benefit from all kinds of immigration, to an extent - the most highly skilled through to the least skilled... but that doesn't mean we couldn't control immigration to lower the proportion of the total which is undesirable.
For example, if we need seasonal workers we could could have arrangements whereby enough are allowed in - we have done, very recently.
How do you know which are undesirable? The answer is you don't, e.g. you let in a certain number of factory workers and toilet cleaners, doctors, lawyers, some of them will end up not being so productive as others.
Then there is the problem of knowing how many is enough? To take your example of agricultural workers, would each farmer have to write in with a desired quota? Or will some office try to estimate in advance? How do you adapt numbers dynamical and fast enough, what if the strawberry season comes months earlier, or there is a larger crop that will require more workers, or a drought means the crop is a failure and few of the workers are needed? Why not simply let a free market dictate the ebb and flow of workers rather than add cost and complexity to the businesses?
Points based visa systems tend to be hideously flawed, I know, I have researched it a lot.
You see it said on OCUK every day that a university degree is useless and doesn't help them with their work etc, and that is often true for individuals. Why exclude a highly productive worker because they don;t hit enough points on some arbitrary point system?
There are much better ways to mitigate possible negative effects of immigration. E.g., people are afraid that immigrants lower salaries for low income workers. there is a simple solution to this, make it illegal to pay an immigrant a salary any lower than the average regional salary of workers doing the same job, and you could go a step further and restrict the benchmark to only those workers with a British passport. The US has the same policy and it effectively eliminates that concern.
If a concern of immigrants is some of them become benefits cheats then the problem isn't the immigrants but flaws in the benefits system, which occurs for British benefit cheats as well. More effective would be mechanisms to reduce such abuse.
No. Do you struggle with comprehension?
So how else do unskilled workers without formal qualifications get tested?
E.g., Hotels need people to make beds and clean the guest rooms, there is no international qualification, no university education or industry certificate. You have to trust them that they can do that job, and obviously most people can, so what exactly are we trying to control?
You're focussing too much on me mentioning age. I mentioned that in the context of having a points system like Australia/NZ/etc - I was making the point that we could have whichever criteria we wanted, then weight them however we wanted. You asked how we assign points to a list of workers, and I said how we can do what we want, or have special lists of important jobs with quotas for eg. plumbers, etc. That's what Australia/NZ/etc do!
No, I'm just pointing out that controlling on arbitrary factors is fairly useless.
So we can disregard age and education, family ties is already in place for non-Eu immigrants. What else are we going to try and award points for? I know Canada awards points for French language ability, we could do the same for Welsh, Cornish and Gaelic?
And your point about Spain and France kicking out/banning Brits retiring there is still retarded, like before. Some might not get visas, but many will given they'll have pensions which are enough to support themselves, so won't be a burden (health insurance might be mandatory, to make sure that's the case). When you have pensioners like that, states like Spain and France won't block them out of spite - they're the sort of people countries want!
So old people will also be able to emigrate to the UK, so we have decided that we shouldn't discriminate based on age?
I understand the desired goal to control immigrants such that only productive immigrants can enter. The issue I have is that is more or less impossible to determine a priori, is costly and fills businesses with red-tape, is ineffective and overtly complex for what the UK needs from migrant workers. If it was only the case that the UK needed skilled, highly educated workers then I could possible see some merit but that isn't the case, the UK needs both skilled and unskilled.
I prefer to look at objective measures f populations, and that clearly shows that EU immigration is a large net positive, so there isn't an underlying problem with current immigration levels that is of concern. Sure within current EU immigration there is some percentage of unproductive migrants but you will never be able to stop that, even with a points based system. The migrant demographic the UK sees the highest rate of negative fiscal contributions is the non-EU migration, which is heavily controlled. That just highlights the ineffectiveness of it.