The website never sleeps. Many people browse websites late at night where most businesses are closed. The website enables your business to stay open or online 24 hours a day, 7 days a week 365 days a year. A website is more valuable than paying a worker a month to give customers information.
Your rival (competition) has a website. If you have a rivalry with another business that has a website, then it is clear that it has a bigger advantage than your business, especially if they pay for marketing their website in different ways to grow their business.
Do you know 3 Billion people? More than 3 billion people are now using the Internet. According to the Small Business Administration about 50% of sales are from new customers. Having a website means you will significantly have customers no matter what service you offer.
Everyone can see the website not just the city where you have your business. Most small businesses only provide services to the community to which they belong. When you have a website you can offer your services or sell your products all over your continent and beyond if you want.