There are several changes that need to be made to retail law, to stop predatory practices.
Firstly there is one thing that legislators usually do wrong:
The trick is in making law is to make the rules general and mild. For example a law banning cafés from giving away plastic toys is a defective law. The toy manufacturer will just sell them to a different type of business to be given away for free. And it says nothing about other kinds of plastic wastage (or non plastic wastage). And what if there is a good reason to be giving away toys, like birthday party - it should still be possible.
A good version of this law would be a general tax (not a ban) on plastic. So it becomes expensive to give away plastic toys, but also to do other wasteful things with plastic. Only when there is a real utility to using the plastic will businesses be willing to pay the tax.
Here are the changes needed right now.
Sneaky price changes/inflation (Targeted mostly at airlines) The seller must post a sign on the item one week before to one week after the price change. Just having to inform customers should dissuade sellers from most frivolous increases. Price changes cannot be more than 10% per week. Different customers cannot be charged different prices for the same thing on the same day. This also discourages charging very high prices for new products, because it will be difficult to reduce the price later.
Sales tax is a function of the weight of packaging in each material, per weight of product. Very high tax rates for non-recyclable packaging. Most territories already have variable VAT rates for different categories of items, so there's no technical challenge here.
Tax on the production or import of bad things like plastics, coal, wild animals, non-managed wood.
Encourage repairability Targeted at dishwashers, cars. Each package has a parts list. For each part, is it replaceable, are replacements currently being made by more than one manufacturer (not patented)?
Anything sold without a guarantee suffers a higher VAT. The rate reduces in function of the lifespan of the thing. So disposable and bad quality things become expensive.
The wholesale price must also be available. Markup of >100% not allowed. Not only does it let people see which things are over-priced by the retailer, but it lets retailers see what other ones are paying the wholesaler. So it has a deflationary effect on both the retail and wholesale markets.
Things sold in units of 1, 2 or 5 only. So 1000g bags of flour are permitted. But selling a 950g bag will incur a charge. These odd quantities are nearly always scams. There's not normally a good reason to sell 190g or 480g or something.
It's important to have a mechanism for people to report non-compliance, and for the fines on businesses to be public.
As always when raising a tax, it increases the cost of living, so something else must be changed to compensate, like UBI, the dole and minimum wage, income tax, the general VAT rate. This is another thing legislators usually neglect.
Each of these has negative consequences, but all of them can be easily fixed. But this post is already long enough.