People have always put in speculative job applications. I cannot see the problem from your end. Your job is to sift, and since most applicants are weeding themselves out with errors, they're doing most of your work for you.
I guess that in today's job market, some applicants become jaded. They should try hard, but I can see how it happens. I agree with IAmFluffy that many young people are very impressive indeed in qualifications and attitude. I dislike 'in my day' carping from people who are lucky enough not be trying to find their first job at this time.
Like I said, I don't usually play the grammar cop on here. We all make mistakes, but people who make them while complaining about the shortcomings of others do present something of an open goal.
And though my own grammar isn't perfect, I don't find it that hard to construct reasonably literate posts. In fact, I'd find it harder to have two styles.
I interview for roles from time to time. I look for various things. Accuracy and attention to detail are important for my job, but the correct attitude and aptitude is probably more valuable, so I wouldn't necessarily discard an application with the odd spelling mistake if I thought the candidate might have something to offer.
I let them explain themselves at the interview. To me, that's the important point of the recruitment process, not the path to it.