I'll just say that a lot of the complexity in the IRC is caused by the fact that life, and especially business, is complex. It might sound simple, but "income" is tough to measure. And there is a lot of complexity in there as a gateway to tax avoidance for favored industries, but just as much to close loopholes for smart companies who take simple rules, twist them into something unrecognizable, and on the other side you've turned an economic gain into a huge taxable loss.
Point is, yes, we could vastly simplify the IRC and make tax compliance easier, but it's a LOT easier said than done, and can't be done without trade-offs elsewhere. It's funny - every time tax reform comes up someone will say CPAs must oppose it because it will eliminate the need for them!! OH NOOO!! I can promise, no one in tax is worried about Congress making things simple enough to threaten anyone's job as a tax professional.
What would help, and eliminate some jobs at H&R Block and the like, is for IRS to pre-prepare returns and send them out for signature. For some large majority of us, all the information on the return is reported to IRS on 1099s and 1098s, W-2s, etc. and IRS could do a perfect return quite easily and all individuals need do is, if they don't itemize, sign and send in with a check, and for those that do itemize, add charity, maybe some taxes, and send that in. Of course the tax prep lobbies have spent massive sums on lobbying and defeated those proposals.... Got to get their pound of flesh out of working people to prepare the simplest returns.