A much-loved burger restaurant is closing after a wheelchair user sued the restaurant over a ‘high threshold’ that prevented him from entering. The Great American Hamburger & Pie Co.in Richmond, San Francisco, closed last week, citing the lawsuit as the final blow. The owners, George and Helen Koliavas told local media that there were discussions about constructing a wheelchair-accessible ramp, but the cost was too high. Now, they said they have been left with no choice but to close after 38 years in business. The pair said: “We want to thank all our loyal customers who have made our business …