Yes, there are roadside places in Hawaii. It's not all four-star resorts, ersatz tiki bars and national franchises. There are roads, after all; along the roads, away from the tourist areas, are many places to have a genuine roadside experience.
The Hawaiian Style Café, in the town of Waimea (also known as Kamuela) on the Big Island, is one of those places. Double screen doors open onto a horseshoe-shaped counter and about a dozen booths and tables, almost always fully occupied from opening to closing (7:30 till 1:30 seven days a week).
Breakfast is served any time and the "specials" board lists a dozen or so items daily. Though much of the menu is typical diner fare, items such as banana macadamia nut pancakes and Kailua pork-sweet Maui onion omelettes tell you you're not on the mainland.
The food is very good and the portions are huge - almost legendary, in fact.

Above: a typical lunch for two. On the left, a fresh grilled mahi mahi sandwich, a scoop of macaroni-potato salad and a huge pile of fries, about $9; on the right, chicken katsu (two chicken cutlets, breaded Japanese-style with grilled onions and gravy), Korean barbecued steak, two scoops of rice and one of mac-potato salad, about $10. Hungry yet?
With over 1500 restaurants in the US and a dozen other unfortunate counties, his signs are everywhere - towering over freeway off-ramps, lining downtown arterials, visible out in the middle of nowhere. While most of us would admit to having visited a Denny's, we'd also probably be quick to add that it was under duress (read: late at night, on the freeway, nothing else open for miles, we were with friends who didn't know better, if we'd had a choice we wouldn't have, but ...).
Grave Creek Bridge sits astride the Old Pacific Highway about 15 miles north of the town of Grants Pass in southern Oregon. The 105-foot-long bridge was built in 1920 and thoroughly restored by the State of Oregon in 2001.
Just outside the small town of Zillah in central Washington State stands a premier example of roadside architecture - the Teapot Dome Service Station. Built in 1922 and named after the infamous Teapot Dome oil-lease scandal, the station was originally located about a mile east of where it now sits, on an original alignment of the Yellowstone Trail at a tiny spot called Dalton. The building was hand-crafted by Jack Ainsworth; it has a conical roof atop a circular frame, a sheet-metal handle and a cast concrete spout.
In the early days of highway travel it was apparently considered quite a novelty to drive one's auto through a tree (intentionally, of course). More than a half-dozen such attractions were to be found up and down the West Coast, most of them in the redwood/giant sequoia area of coastal California where trees are TREES. A few still exist, such as the Chandelier Tree, located just off the Redwood Highway (US 101) near Leggett; others like the Wawona Tunnel Tree in Yosemite Park are gone.