Several reasons actually, here are a few. Firstly, there are no real accredited licensing bodies for roofers and nothing to regulate their experience or knowledge; therefore, almost anyone with a ladder can tell you they are a roofer. Installing a roof incorrectly will void the manufacturer's warranty and it's as simple as nailing the shingles too high for the roof to fail and leak or blow off. Someone new or inexperienced may have underbid the job, left out important details or simply is cheap because they aren't in business for the long haul. All companies may not have adequate insurance and roofing is a risky business, therefore proper insurance is expensive. They may not have WCB-Worksafe BC coverage or a proper liability policy. Remember if someone is hurt on your home and they are not properly insured it becomes your problem. Read the TC Article from March 17, 2012 (link at the bottom of the home page) about inadequate insurance where former Premier Gordon Campbells experience is highlighted. They are using inexpensive and unproven materials. Just because the products/shingles they are using come with a great looking warranty it isn't always what it seems. We have seen new inexpensive manufacturers enter the market with good warranties. Problem is that if and when the product fails, new companies often go out of business and aren't around to honor their warranty. We use top notch manufacturers that we have used for years. If there is a problem with a batch of shingles, they are there to honor the warranty and make it right. Try checking the BBB as well. What is the reputation of the company, do you know anyone who has used them, ask for references. Another cause for concern, a company that requires a deposit up front. This may be an indication their financially strained or don't have good credit with a supplier. You get what you pay for with Phil Smith Roofing. We guarantee you won't get a better job!