My son goes out for the day every weekend, so I have to give him
transportation fee and lunch money every time he does so.
I'd like to know if the above sentence sounds natural to native
speakers. My concerns are:
Is there any way to make the expression "transportation fee and lunch
money" shorter? I'm wondering if it can be described as "xx for
transportation and lunch".
Is it awkward if I omit "he does so" and put the period after "time"?
Not just if you omit “he does so”; the entire sentence does not sound natural.
The word transportation (instead of transport). There's nothing wrong with the word transport, as it is. It is the natural and normal way for English (and other British) people to use the word. Also, putting the word money after the word lunch is not natural. It's more natural to say money for lunch.
The first part of your sentence, “My son goes out for the day every weekend”, is unclear. There is more than one day in weekends. Do you mean that he goes out for one day or both days, every weekend? If it’s one day, you can say “My son goes out for one day every weekend.” If it’s both days, you can say “My son goes out for the day, every Saturday and Sunday.’
Therefore, your sentence can be: “My son goes out for one day every weekend.” Or, “My son goes out for the day, every Saturday and Sunday, so I have to give him money for transport and lunch, every time."
This would be the more natural and common way to say it, at least to me as a speaker of British English.