Be careful here; don't get confused, please. Base salary is a term of art for the total amount of your salary but not any bonuses or commissions.
If you have a base salary of US$5000 per month, you'll find that taxes and your share of health insurance (etc) are deducted from that base salary. Take-home pay means the amount left over after these deductions.
These deductions do indeed take a big chunk out of your take-home pay. Still, when you apply for a loan or a new job, you can tell them you make a base salary of US$5,000 per month.
Now, if you make $1,000 in base salary, but get paid commissions on top of that, you'll probably have a variable monthly income. If you close a big deal you'll get an extra $10,000 one month, but if your customers are all on vacation you'll get nothing extra in July. That is a more complex story to tell to somebody when you apply for a loan. You'll probably need to show them yearly averages.
The same goes if you get a big bonus one month each year.
Yes, it's annoying that there are so many deductions from your paycheck. If you don't want that, you can work (in the US) as an independent business person. But then you have to handle your own estimated-tax payments, benefits, retirement savings, unemployment, life insurance, and all the other deductions.