Everyone gets anxious sometimes but some people have disordered anxiety. It is uncontrollable, disproportionate, and prevents them from completing daily living activities or being able to move around and plan journeys.
PIP isn't given for diagnosis, it is given based on the level of need and evidence provided to back up those claims.
Similarly depression. Everyone has low moods, every one has hard times every so often, every one finds themselves in a hard situation from time to time but depression is a disordered low mood which doesn't just stop people from completing daily living activities or being able to move round and plan journeys, it stops some people living.
Not to mention anxiety covers a large spectrum of disorders: generalised anxiety disorder, panic disorder, agoraphobia, social anxiety disorder etc. There are some associated disorders related to anxiety: ocd, selective mutism, separation anxiety, ptsd, cptsd, acute stress disorder etc.
It's not a little bit of the worries. These conditions can be absolutely debilitating.
Let's go through depression. We've got: major depressive disorder, persistent depressive disorder, bipolar disorder, cyclothymic disorder, pmdd, psychotic depression, situational depression, melancholic depression, catatonic depression, treatment resistant depression, and then some other depressions like: postnatal depression and atypical depression.
You can't just lump anxiety, or depression all in one basket and say bin them all off they're all the same, work will absolutely help them, force their hand, give them a time limit to recover, get them into therapy give them a few rounds of ineffective CBT, blame them for not complying because of the constraints of their disability and blame them further.
Feeling a little bit anxious every so often isn't going to get you PIP. Don't fall for the bullshit.