Actually 28% of RD$156.25 is RD$43.75 so he did not get any bargain nor did he was charged any more than anybody else. It's something you get used to when living here.
Another advantage of having a company here, lots of 16% ITBIS you can recoup when you charge your clients ITBIS. E.g. you buy RD$3.000 worth of cleaning supplies, which includes 16% ITBIS. You get the ITBIS back by substracting it from ITBIS payments of your clients to you, therefore, the cleaning supplies really cost you only RD$2586 at the end.
Same with phone service, a $2000 monthly bill costs you just $1724 at the end after you get your ITBIS credit calculated.