If you can't normally make someone quickly feel comfortable with you one-on-one, then that is on you. It has little to nothing to do with ages and environments so much as it does your approach, look, and demeanor.I understand what you're saying and I agree to some extent. But I don't think that is ALWAYS the case. If you're performing for someone who has just lost a family member no matter how good you are, unless you bring him back to life they're not going to care. Keep in mind that my comments are made in reference to street magic although im not sure if that is the setting the OP was performing in) If you approach a 12 year old and ask to "show him a magic trick or something cool" he has no idea what is about to happen, if you're in a group you feel more secure and open but if you are alone you tend to be reserved and insecure since you have no idea whats going on, this person may hustle you, con you , take your money and dump you in an alley its natural to want to get the hell out of there. They may open up a bit later but at first I find they're always reserved.
- Jenai
As far as performing for someone who has just lost a loved one goes, I'm assuming the performer in your scenario does not have this information--in which case he should not make this assumption and excuse himself from self-critique, but instead assume it was something he did, as always, and reflect on what he could have done better.
I still disagree with you on both accounts.
Own what you do. Always put it on yourself and grow from it. No excuses. Ever.