Market Cap is not a fair measure of company size
Market cap is simply a measure of what shareholders value a company at.
Unfortunately a comparison of Apple shares vs Microsoft and Intel shares isn't exactly fair as there is a key difference between them: Apple does not pay dividends.
For shareholder return on investment, they can only sell for a profit, which drives the share price up. As Apple is the golden boy of the market, prices will remain high, and people will continue to drive up share prices. But this means Apple's valuation is artificially high.
For a better indication of company size, try looking at equity (total assets minus liabilities). Apple may have a wickedly high market capitalization, but it has a smaller equity than Intel.