Referring to the general tax policies, which are usually being alluded to by these criticisms, as loopholes is disingenuous. We aren't for the most part talking about loopholes, we're talking about considered and intentional tax policy choices. Those intentional policy choices are often referred to as loopholes because doing so obfuscates the reality that such policies are chosen because of the benefits they provide (or harms they avoid).
I suppose we could refer to it as a loophole that someone doesn't get a speeding ticket if they drive 50 mph because the law only makes driving over 55 mph a violation. Or maybe we could consider it a loophole that someone making less money only pays a 15% tax rate because their income is below the level at which a higher rate kicks in. Or we could consider it a loophole that someone isn't guilty of theft if their possession of someone else's property is pursuant to that someone else's permission. But such usages of the term loophole are assaults on its meaning, rob it of its import, and undermine its utility.
We're talking about the intentional choice to, when it comes to income taxation, regard income as occurring where value is created rather than where it is realized. There are reasons why nations - most advanced economies of the world - choose that general tax policy. It is, in their assessment, to their benefit. For instance, they don't want to forego the ability to tax (as income) value-creating economic activity which occurs within their respective nations in order to be able to tax (as income) value-realizing economic activity (i.e. sales) which does. It wouldn't be practical to tax (as income) both (e.g., because of the tax / trade policy wars that would set off), so they choose to tax the former. The advanced economies of the world have, in effect, agreed to settle on taxing the former. But that only works if most everyone goes along with the choice. Many nations then get the other piece of the puzzle - taxes from sales which occur within their respective nations - by applying a hefty value-added tax. Then, for rhetorical purposes (as large swaths of electorates don't really understand why it's done this way and/or want scapegoats to vilify) politicians criticize these intentional tax policy choices which have, for good reasons, been made - often, disingenuously, by referring to the intended effects of them as loopholes.
People often also pretend that income taxation of corporations is comparable to income taxation of individuals so that they can argue that it's reasonable for those corporations to pay as high a (or a higher) rate. Those things aren't comparable in that way. Taxation of corporate income represents an additional level of taxation on top of what individuals pay on their own income (to include that income derived from equity ownership of corporations). The same income which corporations pay income taxes on is typically taxed again when it's realized by its owners.
