Note that the sum of wage + tips must reach the minimum wage, or else the employer is required to make up the difference. It's a common misconception that tipped workers can earn less, in total, than minimum wage.
In just a quick look, I found this:
> 5. Wage theft is particularly acute in food and drink service, and restaurants across the country have been found to be in violation of wage and hour laws. It is true that the law requires restaurants to ensure that tipped workers receive at least the regular minimum wage when their tips are included, but the reality is that huge numbers of restaurants—helped by too-weak enforcement efforts—ignore these requirements. In investigations of over 9,000 restaurants, the U.S. Department of Labor (DOL) found that 84 percent of investigated restaurants were in violation of wage and hour laws, including nearly 1,200 violations of the requirement to bring tipped workers’ wages up to the minimum wage. Among the restaurants that were investigated, tipped workers were cheated out of nearly $5.5 million. Workers in the food and drink service industries are more likely to suffer minimum wage violations than workers in other industries. [0]
EDIT: Apparently the DOL study was focused on 2010-12, so not sure what the newest compliance looks like [1].
[0]: https://www.epi.org/blog/seven-facts-about-tipped-workers-an...
But tips are also often used as a performance evaluation metric, and falling low enough that the employer has to make it up often leads to termination, so, where this is possible (as it most obviously is where cash tips are involved) its not uncommon for employees to be incentivized to artificially inflate tips.
Eliminating the lower tipped based minimum wage (which, when followed, means that tips actually go to the employer, not the tipped employee, to a point) means that, even where this practice and pressure exists, it doesn’t leas to suppressing wages below the general mininum.
Also, I don't see any reason why violating the law in that way should be any more common than violating it by paying non-tipped workers less than minimum wage. Either one would require the same degree, and same kind, of fraud. So tipped workers should be no worse off in practice than non-tipped workers.